Prop. Type: ENG/STIS/P Category: ID: 10000 Cycle: 12 Title: STIS Pure Parallel Imaging Program: Cycle 12 PI: Paul Goudfrooij This is the default archival pure parallel program for STIS during cycle 12. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10001 Cycle: 12 Title: Locating Ultraluminous X-Ray Sources PI: Philip Kaaret We propose to observe ultraluminous X-ray sources which are located near objects bright both in the X-rays and the optical using Chandra and HST. The presence of these reference objects will allow us to tie the x-ray and optical references frames and achieve 0.1-0.2 arcsecond relative position accuracy in searching for optical counterparts to the ultraluminous x-ray sources. This will be a significant improvement over the accuracy previously obtained for most ULXs {limited by Chandra's absolute astrometry} and will should permit identification of individual counterparts. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN ID: 10002 Cycle: 12 Title: Detailed Study of X-ray Jets from a Complete Survey PI: Eric Perlman We propose deep followup HST and Chandra observations of two X-ray jets, which are the X-ray brightest discovered in our Chandra survey of quasars with known radio jets. With these data, we will compare their X-ray, optical and radio morphologies. We will also obtain X-ray and optical spectral indices, and spatially resolved SEDs from the radio through the X-rays. This will allow us to determine the X-ray emission mechanism at each point in these jets, and test critical predictions made by each mechanism. We will also be able to track any changes in physical conditions {including magnetic field and bulk Lorentz factor} that are present in the observed 90 degree bends. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10003 Cycle: 12 Title: Deep Chandra and Hubble Observations of NGC4697, the Nearest Optically Luminous, X-ray Faint Elliptical Galaxy PI: Craig Sarazin We propose 4 new Chandra observations of NGC4697, the nearest X-ray-faint, optically-bright elliptical, which was resolved into low mass X-ray binaries {LMXBs} in Cycle 1. We will detect LMXBs at least three times fainter {~1e37 ergs/s} than possible for any luminous E galaxy at present, allowing a direct comparison with the LMXBs in our Galaxy and M31. We will measure the variability of sources on times up to 4.5 yr. Models predict variability for LMXBs in early-type galaxies, which is particularly strong for the brightest black hole sources. We also propose 1 orbit of HST to detect >1500 globular clusters {GCs}. If the results for luminous LMXBs continue to low LX, most of the LMXBs will be identified with GCs. We will study the formation history of LMXBs, GCs, and field stars in N4697. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN ID: 10004 Cycle: 12 Title: The Physics of Relativistic Jets: Chandra Imaging of Extended Jets in Gamma-loud Blazars PI: F. Tavecchio Extended jets have been a key target for Chandra yet only recently has the kpc-scale jet physics been compared to that of the inner, parsec-scale jets. Such a comparison reveals the jet deceleration, power dissipation, pressure gradient, and confinement mechanism --- all essential ingredients for understanding the relativistic jets that characterize radio- loud AGN. Currently, few data exist to make this comparison. We propose to double the sample, with Chandra observations of 4 gamma-loud blazars: 0954+556 and 1229-021, the only 2 bright radio jets not yet observed by Chandra; and 0208-512 and 3C 454.3, observed in A03 with much too short exposures. We also propose HST multi-band ACS imaging of jet knots in 0208-512, 0954+556 and 3C 454.3. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10005 Cycle: 12 Title: A Uniform Study of Globular Cluster X-raySources: The Keys to Cluster Dynamical Evolution PI: Walter Lewin We propose to extend our ongoing studies of the dynamical evolution of globular clusters by observing their populations of low-luminosity X-ray sources. Many of these sources are binary systems {or have evolved from them} and hold the key to the clusters with widely different physical properties such as central concentration, cluster size and mass, which are all key ingredients in the formation and evolution of binaries. To make this study as uniform as possible, the clusters will be observed to the same limiting luminosity. Numberical simulations with the world's fastest computer will assist in the interpretation of our observational data. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10006 Cycle: 12 Title: Black Hole X-ray Novae in M31 PI: Michael Garcia During A01-3 we found 22 Black Hole X-ray Novae {BHXN} in M31 using Chandra, and with HST {WFPC2} found two optical counterparts. Our results suggest either a surprisingly high ratio of BH to NS binaries, or a surprisingly high duty cycle for BHXN. We propose to continue this program, with the goals of understanding the relative number of BH vs. NS X-ray binaries in the M31 bulge, and determining the orbital period distribution and duty cycles of these BHXN. Continued observations can determine the duty cycle. The new ACS will allow us to go 2 mags deeper than the WFPC2, and could triple the number of optical counterparts and therefore orbital period estimates. M31 is the only galaxy near enough to allow this extragalactic survey for BHXN. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10007 Cycle: 12 Title: The Spectral Energy Distribution of Cen X-4 PI: Michael Garcia We propose to obtain the first high-quality, wide-band spectral energy distribution {SED} of the neutron star X-ray nova Cen X-4 in quiescence. We will compare this SED to those we have previously obtained for black hole X-ray novae {BHXRN} in quiescence. Our previous comparisons of SEDs have been very powerful in revealing the nature of these exotic objects; for example, they have revealed the best evidence yet for the existence of event horizons. These wide-band, high quality SEDs have revealed the presence of ADAFs in BHXN, and are revealing the presence of winds {ADIOS} and/or convection {CDAFs} in these flows. Previous SEDs of Cen X-4 have suffered from non-simultaneity and have not included the FUV, where the emission may well peak. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10008 Cycle: 12 Title: The Supersoft Source 1E1339.8+2837 and Globular Cluster M3 PI: Jonathan Grindlay We propose two HST orbits, nearly simultaneous with our approved Chandra Cycle 5 program, to study the supersoft source 1E1339.8+2837 and other accreting binaries in the globular cluster M3. Using the ACS/HRC, we will obtain excellent photometry on the recently identified optical counterpart of 1E1339.8+2837 in the F220W, F250W and F330W bands. Using the ACS/WFC, we will survey M3's central regions in B, V, and I to identify counterparts to other Chandra sources, and also obtain excellent B, V, and I photometry of the supersoft source. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10009 Cycle: 12 Title: Galactic Bulge Deep Survey PI: Jonathan Grindlay We propose a deep survey in the second lowest extinction {after Baade's Window} region in the galactic bulge, the window identified by Stanek {1998} at l, b ~0.25, -2.1. This will complement our deep HST/Chandra survey of Baade's Window carried out in July 2003 and allow comparative source populations, and constraints on the gradient towards the galactic center, to be derived. Nine HST orbits are requested to do the optical identifications in this field down to Mv ~ 9, sufficient to identify most CVs and qLMXBs. This will constrain the compact object populations in the galactic bulge. ------------------------------------------------------------------------------ Prop. Type: CAL/AST Category: ID: 10010 Cycle: 12 Title: Long Term Monitoring of FGS1r in Position Mode PI: Edmund Nelan It is known from our experience with FGS3, and later with FGS1r, that an FGS on orbit experiences long term evolution, presumably due to disorption of water from the instrument's graphite epoxy composits. This manifests principly as a change in the plate scale and secondarily as a change in the geometric distortions. These effects are well modeled by adjustments to the rhoA and kA parameters which are used to transform the star selector servo angles into FGS {x, y} detector space coordinates. By observing the relative positions of selected stars in a standard cluster at a fixed telescope pointing and orientation, the evolution of rhoA and kA can be monitored and calibrated to preserve the astrometric performance of FGS1r. ------------------------------------------------------------------------------ Prop. Type: CAL/AST Category: ID: 10011 Cycle: 12 Title: Monitoring FGS1r's Interferometric Response as a Function of Spectral Color PI: Edmund Nelan This proposal obtains reference point source Transfer Functions {S-Curves} for FGS1r through the F583W filter and the F5ND attenuator at the center position of the FGS1r FOV for a variety of stars of different spectral types. These Transfer Functions are needed to support the analysis of GO science data for the study of close and wide binary star systems and for determining the angular size and shape of extended sources. This proposal observes stars that have been observed in previous cycles to monitor the long term evolution of the FGS1r S-curves. This proposal also {1} monitors the FGS1r Lateral Color response {using stars Latcol-A and Latcol-B}, {2} calibrates the "Pos/Trans" bias of a star's position as determined from Transfer mode and Position mode observations, and {3} calibrates the shift of a star's centroid when observed with F5ND relative to that when observed with F583W. ------------------------------------------------------------------------------ Prop. Type: CAL/AST Category: ID: 10012 Cycle: 12 Title: F583W/F5ND Cross Filter Calibration FGS1r Off Center PI: Edmund Nelan This proposal calibrates the shift of a star's position when observed through the F550 filter and F5ND attenuator relative to the F583W filter at locations off center in the FGS1r FOV. This calibration is necessary to support ongoing multi-cycle FGS astrometry proposals {extrasolar planet astrometry and the Cepheid distance scale in particular}. ------------------------------------------------------------------------------ Prop. Type: CAL/OTA Category: ID: 10013 Cycle: 12 Title: Focus Monitor PI: Stefano Casertano The focus of HST is measured from WFPC2/PC and ACS/HRC images of stars. Multiple exposures are taken in parallel over an orbit to determine the influence of breathing on the derived mean focus. Observations are taken of clusters with suitable orientations to ensure stars appear in all fields. ------------------------------------------------------------------------------ Prop. Type: CAL/OTA Category: ID: 10014 Cycle: 12 Title: Spectrophotometry of FAINT IR STANDARDS PI: Ralph Bohlin Faint spectrophotometric standard stars required for COS and the SBC channel on ACS have been established via the STIS FASTEX program that has executed over the last three cycles. Cycle 12 is an especially opportune time to establish companion faint IR standards for WFC3, because the NICMOS proposal 9998 includes observations in cycle 12 of all 6 of the primary standard stars in order to establish the absolute flux calibration of the three grism modes to 1%. In addition to WFC3, these new faint secondary IR standards will be a significant step towards establishing flux standards for JWST, as well as for SNAP, SIRTF, and SOFIA. The 6 primary standards included in Propid=9998 are in the range of V=11-13 and include three hot pure hydrogen WDs and 3 solar analogs. We propose to establish new IR faint standards in the 15-17 mag range. Appropriate spectral types for faint IR standards are solar analogs and hotter WDs. Many M type and cooler stars are variable, so that long term monitoring is required before committing HST time to such cool stars. A few G type and WD faint stars will provide a set of faint IR standards with minimal sky and color coverage. Existing HST images of any candidates can provide verification that there are no contaminating stars above the 1% level within 2-3arcsec. However, the ACS calibration field in 47 Tuc is too crowded for linking to ground based observations. If the other candidates are selected from SDSS or other ground based data, then the NICMOS and STIS acquisition images can provide this verification, as well as correction factors for arbitrary photometric size apertures. The SNAP team is providing the northern faint stars using unreleased SDSS data. In addition, the extreme coolest types such as L and T stars have proven essential to sorting out the long wavelength QE of ACS; both the ACS and eventually WFC3 calibrations could be improved with knowledge of L and T SEDs in the region beyond 0.95 microns. In addition to the primary purpose of ACS QE vs. wavelength and broad band F814W and F850LP calibrations, these three stars in C.} below are at the flux level required for WFC3 grism calibration. The brighter M, L, and T standard stars will each require a NICMOS orbit, while each faint standard requires two Nicmos orbits and one STIS orbit for complete wavelength coverage. The STIS spectra of the M and L stars are done as ACS calibrations in cycles 12 and 11, respectively. An additional faint WD has already been proposed for 2 Nicmos and 4 STIS orbits in their cycle 12 programs already. See Table 1 for a summary of the 18 orbit allocation for this program 10014. Bright stars in the V=0-6 mag range would be useful for direct comparisons to NIST calibrated lamps. This comparison would offer the opportunity to compare two fundamentally different realms of physics: pure hydrogen stellar models and laboratory black body physics. Unfortunately, the Nicmos bright limit is V=~8 for a solar analog and a 1s exposure without defocussing the OTA. The primary Sloan standard BD+17d4708 at V=9.9 is safely fainter than this Nicmos limit. ------------------------------------------------------------------------------ Prop. Type: CAL/OTA Category: ID: 10015 Cycle: 12 Title: Cross-Instrument Photometric Transformations PI: Stefano Casertano This program will obtain NICMOS photometry of two regions in the ACS calibration field in 47 Tucanae, with the purpose of enabling cross-calibrations between NICMOS and WFC3. The proposal will require two orbits. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10016 Cycle: 12 Title: STIS CCD Performance Monitor PI: Linda Dressel This activity measures the baseline performance and commandability of the CCD subsystem. Only primary amplifier D is used. Bias and Flat Field exposures are taken in order to measure bias level, read noise, CTE, and gain. Numerous bias frames are taken to permit construction of "superbias" frames in which the effects of read noise have been rendered negligible. Full frame and binned observations are made, with binning factors of 2 x 1, 1 x 2, 2 x 2, 4 x 1, and 4 x 2. Bias frames are taken in subarray readouts to check the bias level for ACQ and ACQ/PEAK observations. All exposures are internals. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10017 Cycle: 12 Title: CCD Dark Monitor-Part 1 PI: Linda Dressel Monitor the darks for the STIS CCD. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10018 Cycle: 12 Title: CCD Dark Monitor-Part 2 PI: Linda Dressel Monitor the darks for the STIS CCD. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10019 Cycle: 12 Title: CCD Bias Monitor - Part 1 PI: Rosa Diaz-Miller Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10020 Cycle: 12 Title: CCD Bias Monitor - Part 2 PI: Rosa Diaz-Miller Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10021 Cycle: 12 Title: CCD Read Noise Monitor PI: Linda Dressel This proposal measures the read noise of all the amplifiers {A, B, C, D} on the STIS CCD using pairs of bias frames. Full frame and binned observations are made in both Gain 1 and Gain 4, with binning factors of 1x1, 1x2, 2x1 and 2x2. All exposures are internals. Pairs of visits are scheduled for bimonthly execution. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10022 Cycle: 12 Title: STIS CCD Hot Pixel Annealing Cycle 12 PI: Jesus Maiz Apellaniz The effectiveness of the CCD hot pixel annealing process is assessed by measuring the dark current behavior before and after annealing and by searching for any window contamination effects. In addition CTE performance is examined by looking for traps in a low signal level flat. Follows on from proposal 9612. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10023 Cycle: 12 Title: STIS CCD Spectroscopic Flats C12 PI: Charles Proffitt Obtain CCD flats on the STIS CCD in spectroscopic mode. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10024 Cycle: 12 Title: STIS CCD Imaging Flats C12 PI: Charles Proffitt Investigate flat-field stability over a bimonthly period. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10025 Cycle: 12 Title: STIS CCD Spectroscopic Dispersion Monitor PI: Scott Friedman Obtain a wavecal deep enough to constrain wavelength and spatial distortion maps without overusing the calibration lamp - to supplement the Cycle 11 9617 program. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10026 Cycle: 12 Title: STIS Sparse Field CTE test-internal {Cycle 12} PI: Paul Goudfrooij CTE measurements are made using the "internal sparse field test", along the parallel axis. The "POS=" optional parameter, introduced during cycle 11, is used to provide off-center MSM positionings of some slits. All exposures are internals. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10027 Cycle: 12 Title: CCD Sparse-Field CTE External C12 PI: Paul Goudfrooij This program will allow the derivation of accurate coefficients which can be used to correct low count level data {both imaging and spectroscopy} for nonlinearity/CTE effects. Dependences on x-position, background sky level, and time dependence will be quantified in addition to accurate determination of intensity and y-position effects in a fourth epoch and to higher accuracy than previously determined. With these corrections the effect of CTE can be calibrated in order that no science data should have additional induced photometry errors in excess of 1%. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10028 Cycle: 12 Title: CCD Full-Field Sensitivity Monitor C1 PI: Bahram Mobasher Measure a photometric standard star field in Omega Cen in 50CCD mode every few months to monitor CCD sensitivity over the whole field of view. Keep the spacecraft orientation within a suitable range {+/- 5 degrees} to keep the same stars in the same part of the CCD for every measurement. The second observation is performed at an orientation rotated by 180 degrees with respect to the other observations to study the effect of CTE {to first order}. This test will give a direct transformation of the 50CCD magnitudes to the Johnson-Cousins system for red sources. These transformations should be accurate to 1%. The stability of these transformations will be measured to the sub-percent level. These observations also provide a check of the astrometric and PSF stability of the instrument over its full field of view. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10029 Cycle: 12 Title: Slit Wheel Repeatability PI: Jessica Kim Quijano Test the repeatibility of the slit wheel by taking a sequence of comparison lamp spectra with grating G230MB {2697} and the three smallest long slits {52X0.2, 52X0.1, and 52X0.05}. This is a clone of Cycle 11 Program 9626. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10030 Cycle: 12 Title: STIS/CCD Spectroscopic Sensitivity Monitor for Cycle 12 PI: Scott Friedman Monitor sensitivity of each CCD grating mode to detect any change due to contamination or other causes. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10031 Cycle: 12 Title: STIS MAMA Cycle 12 Deep Wavecals PI: Alessandra Aloisi This program will obtain deep wavecals for the STIS Echelle modes in order to produce improved dispersions solutions. The new wavelength solution is based on a physical model of the instrument's optical elements and will supercede the empirical polynomial fit. This work is part of the STIS Calibration Enhancement project conducted at the ST-ECF. Deep wavecals are required in order to take full advantage of the new line list from the ESA -funded Pt/Cr-Ne calibration lamp project and to test the predictive power of physical instrument model of STIS. A second epoch of observations will investigate the issue of MSM repeatability. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10032 Cycle: 12 Title: MAMA Full Field Sensitivity Monitor & PSF Check PI: Bahram Mobasher The purpose of this program is to monitor the sensitivity of the MAMA detectors over the full field. This is achieved by observing globular cluster NGC6681 once during Cycle 12. The data can be directly compared with similar data obtained in Cycles 7, 8, 9, 10 and 11. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10033 Cycle: 12 Title: MAMA Sensitivity and Focus Monitor Cycle 12 PI: Scott Friedman Monitor sensitivity of each MAMA grating mode to detect any change due to contamination or other causes. Also monitor the STIS focus in a spectroscopic and an imaging mode. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10034 Cycle: 12 Title: Cycle 12 MAMA Dark Monitor PI: Jesus Maiz Apellaniz This test performs the routine monitoring of the MAMA detector dark noise. This proposal will provide the primary means of checking on health of the MAMA detectors systems through frequent monitoring of the background count rate. The purpose is to look for evidence of change in dark indicative of detector problem developing. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10035 Cycle: 12 Title: MAMA Fold Distribution PI: Thomas Wheeler The performance of MAMA microchannel plates can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the STIS MAMA Fold Analysis {8860} during Cycle 9. ------------------------------------------------------------------------------ Prop. Type: ENG/STIS Category: ID: 10036 Cycle: 12 Title: STIS MAMA Anomalous Recovery PI: Thomas Wheeler This proposal is designed to permit recovery of the FUV- or NUV-MAMA detector after an anomalous shutdown. Anomalous shutdowns can occur as a result of bright object violations which trigger the Bright Scene Detection or Software Global Monitors. Anomalous shutdowns can also occur as a result of MAMA hardware problems. The anomalous procedure consists of three procedures: {1} a signal processing electronics check, {2} high voltage ramp-up to an intermediate voltage and {3} high voltage ramp-up to the full operating voltage. During each of the two high voltage ramp-ups, diagnostics are performed during dark and flat field ACCUMs. This proposal executes the same steps as were in proposals 9630 during cycle 11. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10037 Cycle: 12 Title: STIS Cycle 12 Faint Standard Extension: FASTEX PI: Ralph Bohlin WD 1657+343 is the faintest of four pure hydrogen WD stars that comprised the original FASTEX program and has been observed thrice in 2000 and once in 2002 to firmly establish the absolute flux levels. Annual revisits of one orbit should occur to monitor our predictions of the CTE correction, which is increasing with time on orbit. G430L at both the standard and E1 aperture position are required at the exposure times already established as standard. The remaining time in the orbit will be spent extending the wavelength coverage using G750L. To date, HST has not provided any faint solar analog stars to compliment the three V=12-13.5 mag solar analogs provided by M. Rieke for NICMOS calibration. As instrumentation in space and on the ground becomes more sensitive, fainter flux standards are required. A solar analog in a field with low reddening is an excellent choice for a fainter standard, because unreddened pure hydrogen WDs are rare beyond V=16, because Solar absolute fluxes are well measured at all wavelengths, and because the fluxes do not fall off as fast as the hot WDs at longer wavelengths. A 16.5 G star may not be faint enough for most JWST modes but will provide a significant step in the right direction. The SNAP program requires such a spectrophotometric standard, which lies at the bright limit of its spectroscopy mode. NICMOS grism observation of this standard are planned for cycle 12 and STIS spectra are required to establish the standard over the full range from 0.3-2 microns. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10038 Cycle: 12 Title: CTE measurement and photometric accuracy for extended sources PI: Bahram Mobasher This is a follow-up study to proposal 8839 to study STIS CTE calibration for extended objects. This takes images of galaxies to measure the effects of CTE on the isophotes of galaxies. The aim is to image small {2-3"} extended sources in a suitably rich galaxy cluster. The target, A1689, has been observed by WFPC2 in the WF2 and WF4 chips {in Feb 2000}, so that cross-instrument comparison will be straightforward. One orbit is needed per amplifier, i.e. two orbits total. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10039 Cycle: 12 Title: Spectroscopic Sensitivity Workout: First-order modes PI: Thomas Brown We will observe the primary flux standards G191B2B, GD71 and GD153, obtaining first-order spectra in all L-modes {G191B2B only in the CCD modes due to its high brightness in the UV}. By comparing observed and model spectra, we will update calibration reference files describing spectroscopic sensitivity {and CTE loss} as a function of time. On visit of GD71 will be spent on verifying the recently derived CTE formula for STIS Spectroscopic modes with the CCD, by stepping the target along the slit {7 positions} with two {short} exposure times. This will verify the results using the two-amplifier readout method, and provide high-S/N data at low intensity levels and low background level. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10040 Cycle: 12 Title: Test of new STIS pseudo-aperture positions PI: Charles Proffitt This proposal will check positions and throughputs for E1, E2, D1, and WEDGEA0.6 pseudoaperture positions. The E1 aperture positions have been slightly revised to better reflect on-orbit measurements, and the other new pseudoaperture positions have been recently defined. The new aperture positions divide into three groups: {1} E2 apertures for better row 900 fringe flats: 52X2E2 52X0.5E2 52X0.2E2 {2} D1 apertures for low noise FUV MAMA 1st order spectra: 52X2D1 52X0.5D1 52X0.2D1 52X0.1D1 52X0.05D1 F25SRF2D1 F25QTZD1 25MAMAD1 {3} a new coronagraphic wedge position located at a narrower part of the coronagraphic wedge: WEDGEA0.6 ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: SOLAR SYSTEM ID: 10041 Cycle: 12 Title: Characterization of a planetary-sized body in the inner Oort cloud PI: Michael Brown Our recent discovery of a planetary-sized body in the inner Oort cloud presents the opportunity for quick low-cost survey of this extremely interesting object. With just 2 orbits we will be able to independently determine the size of this object, definitely determine if satellites exist, and search for the shortest timescale photometric variations. As little is known about this body, it is difficult to predict what results will come from these observations, but it is clear that such an object deserves observations at the high resolution that only HST can provide. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10042 Cycle: 12 Title: CCD Daily Monitor PI: Adam Riess This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10043 Cycle: 12 Title: External CTE Monitor PI: Adam Riess Monitor CTE changes during cycle 11. Determine CTE. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10044 Cycle: 12 Title: ACS internal CTE monitor PI: Max Mutchler The charge transfer efficiency {CTE} of the ACS CCD detectors will decline as damage due to on-orbit radiation exposure accumulates. This degradation will be closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs. All the data for this program is acquired using internal targets {lamps} only, so all of the exposures should be taken during Earth occultation time {but not during SAA passages}. This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing {program 8948}, so that results from each epoch can be directly compared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR} data will be obtained over a range of signal levels for both the Wide Field Channel {WFC}, and the High Resolution Channel {HRC}. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10045 Cycle: 12 Title: SBC Dark Current PI: Colin Cox ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10046 Cycle: 12 Title: CCD Hot Pixel Annealing PI: Colin Cox Hot pixel annealing will be performed once every 4 weeks. The CCD TECs will be turned off and heaters will be activated to bring the detector temperatures to about +20C. This state will be held for approximately 12 hours, after which the heaters are turned off, the TECs turned on, and the CCDs returned to normal operating condition. To assess the effectiveness of this procedure, a bias and two dark images will be taken after the annealing procedure for both WFC and HRC. The HRC darks are taken in parallel with the WFC darks. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10047 Cycle: 12 Title: ACS UV Contamination Monitor PI: Mauro Giavalisco A standard star field {NGC6681} is observed every three months, alternating between after and before annealing operations, through all the ACS broad band UV filters. NGC6681 hosts several UV spectro - photometric standard stars for which accurate spectra have been {and will continue to be} measured with STIS. Two SBC dark current exposures taken as the last exposure of each SBC sequence. Also, to minimize SBS turn-on/turn-off cycles and in order to check the lab flats for the SBC detector, internal observations using the deuterium lamp with F125LP are being taken inflight, following the UV monitor observations. The internal flats have been taken ~monthly since SMOV, and the degradation of the lamp has been monitored. The total exposure time to date is ~15 hours giving a total of 8600 counts/pixel. The goal is 10, 000 counts/pixel such that the resulting pipeline flat has uncertainties of ~1% due to poisson counting statistics. Thus, approximately 3 additional hours of observation are required. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10048 Cycle: 12 Title: Stability of the ACS CCD: Flat fielding, Photometry, Geometry PI: Jennifer Mack This program will verify that the low frequency flat fielding, the photometry, and the geometric distortion are stable in time and across the field of view of the CCD detectors. A moderately crowded stellar field, located ~6' West of the center of the cluster 47 Tuc, is observed every three months with the WFC and HRC using the full suite of broad and narrow band filters. The same field has been observed during SMOV to derive low frequency corrections to the ground flats and to create a master catalogue of positions and magnitudes from dithered observations of the cluster. In Cycle 11, this field was observed again using single pointings at various roll angles. The positions and magnitudes of objects are used to monitor local and large scale variations in the plate scale and the sensitivity of the detectors. The Cycle 12 program will continue to monitor these effects and will derive an independent measure of the detector CTE. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10049 Cycle: 12 Title: ACS Internal Flat Field Stability PI: Jennifer Mack The stability of the CCD flat fields will be monitored using the calibration lamps and a sub-sample of the filter set. High signal observations will be used to assess the stability of the pixel-to- pixel flat field structure and to monitor the position of the dust motes. Shorter exposures will be used to identify charge traps and to assess the stability of the DQ arrays. Only internal exposures with the calibration lamps will be required. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10050 Cycle: 12 Title: ACS Earth Flats PI: Jennifer Mack High signal sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the flats currently used by the pipeline and will provide a comparison with flats derived via other techniques: L-flats from stellar observations, sky flats from stacked GO observations, and internal flats using the calibration lamps. Weekly coronographic monitoring is required to assess the changing position of the spots. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10051 Cycle: 12 Title: Subarray Bias PI: Adam Riess This program consists of subarray bias exposures for the ACS CCDs in order to determine any need for such regular monitoring for calibration of supported ACS subarray science. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10052 Cycle: 12 Title: ACS CCD Flash Calibration PI: Colin Cox This activity provides a set of CCD FLASH exposure reference images for each current level/shutter-side/detector combination, for the pair of FLASH LEDs on the instrument side currently in use. It also tests the short-term repeatability at the shortest FLASH exposure times that are expected to be used {1.0 sec}. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10053 Cycle: 12 Title: ACS MAMA Recovery from Anomalous Shutdown PI: Colin Cox This proposal is designed for the initial turn-on of the ACS MAMA detector and to permit recovery after an anomalous shutdown. Anomalous shutdowns can occur as a result of bright object violations which trigger the Bright Scene Detection or Software Global Monitors. Anomalous shutdowns can also occur as a result of MAMA hardware problems. The Initial MAMA turn-on/recovery from anomalous shutdown consists of three tests: a signal processing electronics check, high voltage ramp-up to an intermediate voltage, and high voltage ramp-up to the full operating voltage. During each of the two high voltage ramp-ups, diagnostics are performed during a dark ACCUM. The turn-on is followed by a MAMA Fold Analysis . The complete sequence is contained in visits 1 through 4. If a second execution is required during cycle 12, visits 5 through 8 will be run and another proposal prepared for possible future occurrences. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10054 Cycle: 12 Title: ACS photometric Stability PI: Mauro Giavalisco A set of four spectrophotometric standard stars {GD71, G191B2B, GD153, and HZ43} is observed once with ACS's WFC and HRC through all filters, except the ramp filters, to assess the sensitivity of the instrument and measure accurate photometric zero points. The stars are placed at the centre of the aperture, and two images are taken through each filter. This programme is based on proposals 9020 and 9654 designed for SMOV and Cyce 11, and also on programme 9563 from the interim period. No RAMP filters are calibrated here. The exposure times have been calculated to reach, on average, SNR~350 in the central pixel for broad band filters. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10055 Cycle: 12 Title: ACS Polarization Calibration PI: John Biretta This proposal aims to address several specific issues for the polarization calibration: {1} variations in calibration with position on the detector {field dependence}, {2} dependence on telescope roll-angle relative to the target, {3} orientation of the polarizer axes, and {4} geometric distortion contributed by the polarizers. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10056 Cycle: 12 Title: Extreme Red Stars PI: Ronald Gilliland ACS provides unprecedented sensitivity in the far red, this coupled with recent astronomical pushes to ever cooler objects {e.g. new classifications for L and T stellar dwarfs, and extremely high redshift galaxies} increases the need for extending the photometric calibration to include such objects. We propose observations of 2 stellar objects for which STIS spectra will exist, as well as NICMOS grism. The two targets include a late M dwarf and a T dwarf. The M dwarf provides a temporal check with WFC and new constraint for the HRC. The T dwarf provides new results for the WFC. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10057 Cycle: 12 Title: ACS Ramp Filter Calibration PI: Shardha Jogee We request 3 orbits to observe a well-calibrated region in the Orion Nebula with the primary goal of deriving monochromatic L-flats at specific central wavelengths {lambda_c} for {a} WFC {inner+outer} Halpha {FR716N, FR782N} and [OIII] {FR551N, FR601N} ramp filters. {b} WFC middle ramp filters {FR388N, FR459M, FR505N, FR6546N, FR914M}.{c} HRC middle ramp filters {FR388N, FR459M, FR505N, FR656N, FR914M}. As a secondary goal, we will get an independent check of the wavelength calibration which will be provided by the IDT team from the Cycle 11 program 9671. We request 1.5 CVZ orbits to observe two well-calibrated standard star fields in 47 Tuc with the primary goal of deriving WFC and HRC continuum L-flats for three middle {WFC1-MRAMP} filters: FR656N, FR388N, and FR505N. These filters are selected as they are frequently used to map the Halpha 6563 A, [OII] 3727A, and [OIII] 5007A lines and they include the least {FR388N} and most {FR505N} uniform ramps, based on ground data {ISR ACS 02-01}. These 3 filters should provide a good baseline for testing our approach and gauging the range of non-uniformity in the continuum L-flats. For good spatial sampling, the 2 fields are selected with stellar densities appropriate to WFC and HRC. For good spectral sampling we will step in the central wavelength in steps of 80 A, with 30s exposure at each lambda_c providing good S/N for V=15-20 mag stars. We will use 2K subarrays to reduce the frequency of buffer dumps. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10058 Cycle: 12 Title: Improved wavelength calibration for the WFC G800L grism PI: Jeremy Walsh ACS G800L observations of an emission line star {the WC Wolf-Rayet star WR96} and a compact planetary nebula {LMC-SMP81} will be obtained to provide improved coverage of the field variation of the dispersion solution for the WFC and G800L grism. A direct image and a corresponding grism image will be taken at many different positions across the WFC field. By fitting the emission lines, the field dependence of the wavelength zero point and dispersion will be measured. The WR star was already used in Cycle 11 calibrations and these observations provide improved spatial coverage to map the variation of the dispersion with position. The observations of the fainter planetary nebula provide an independent wavelength calibration for a few points over the field. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10059 Cycle: 12 Title: CCD Daily Monitor PI: Adam Riess This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10060 Cycle: 12 Title: CCD Daily Monitor PI: Adam Riess This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10061 Cycle: 12 Title: CCD Daily Monitor PI: Adam Riess This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10062 Cycle: 12 Title: NICMOS Filter Wheel Test PI: Sangeeta Malhotra This is an engineering test to verify the aliveness, functionality, operability, and electro-mechanical calibration of the NICMOS filter wheel motors and assembly after NCS restart in August 2003. This test has been designed to obviate concerns over possible deformation or breakage of the fitter wheel "soda-straw" shafts due to excess rotational drag torque and/or bending moments which may be imparted due to changes in the dewar metrology from warm-up/cool-down. This test should be executed after the NCS {and filter wheel housing} has reached and approximately equilibrated to its nominal Cycle 11 operating temperature. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10063 Cycle: 12 Title: NICMOS Focus and PAM Grid Tilt Tests PI: Tommy Wiklind The purpose of this proposal is to determine if the focus has changed during the safing of NICMOS during the recent shutdown of the NCS, as well as to determine if the tilt of the PAM needs to be corrected. The program consists of: Visit 01: Focus sweep using NIC2 Visit 02: Focus sweep using NIC1 Visit 03: Uplink of PAM settings {on hold pending evaluation of visit 1 and 2} Visit 04: Focus sweep using NIC3 {on hold pending evaluation of visit 1 and 2} Visit 05: PAM X/Y grid tilt for NIC1 {on hold pending evaluation of visit 1 and 2} Visit 06: PAM X/Y grid tilt for NIC2 {on hold pending evaluation of visit 1 and 2} Visit 07: Uplink of PAM X/Y parameters {on hold pending execution of visit 5 and 6} After the focus sweeps with NIC1 and NIC2, the focus parameters will be evaluated together with a rough estimate of the coma. The results of this evaluation may lead to a decision to perform a focus sweep with NIC3 and/or a measurement of the PAM tilt grid. No measurement of the PAM tilt grid are planned for NIC3. The focus sweeps are based on the normal focus monitoring proposal 9637. The tilt grid measurements are based proposal 8977 {NIC1} and 9645 {NIC2}. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10064 Cycle: 12 Title: Mini-SMOV NICMOS dark current, shading profile, and read noise program PI: Bahram Mobasher The purpose of this proposal is to study the dark current, read noise, and shading profile for all three NICMOS detectors after the NICMOS starts operating due to safing. This proposal is a version of the NICMOS monitoring program. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: SOLAR SYSTEM ID: 10065 Cycle: 12 Title: Mars at Closest Approach PI: James Bell We will take highest-quality HST images of Mars at it's closest approach in ca 50, 000 years. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10066 Cycle: 12 Title: NICMOS Filter Wheel/Mechanisms Mini-Functional Test PartII PI: Megan Sosey This is an early engineering test to verify the aliveness, functionality, operability, and electro-mechanical calibration of the NICMOS filter wheel motors and assembly. This is the FIRST use of the NICMOS filter wheel mechanisms since they were disabled by ground command in January, 1999. This test has been designed to obviate concerns over possible deformation or breakage of the fitter wheel "soda-straw" shafts due to excess rotational drag torque and/or bending moments which may be imparted due to changes in the dewar metrology from warm-up/cool-down. This test should be executed after the VCS {and filter wheel housing} has reached and approximately equilibrated to its nominal Cycle 11 operating temperature. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10067 Cycle: 12 Title: WFPC2 Cycle 12 Decontaminations and Associated Observations PI: Inge Heyer This proposal is for the monthly WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10068 Cycle: 12 Title: WFPC2 CYCLE 12 Standard Darks PI: Gabriel Brammer This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10069 Cycle: 12 Title: WFPC2 CYCLE 12 Supplemental Darks, Part 1/3 PI: Gabriel Brammer This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10070 Cycle: 12 Title: WFPC2 CYCLE 12 Supplemental Darks Part 2/3 PI: Gabriel Brammer This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10071 Cycle: 12 Title: WFPC2 CYCLE 12 Supplemental Darks Part 3/3 PI: Gabriel Brammer This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10072 Cycle: 12 Title: WFPC2 CYCLE 12 INTERNAL MONITOR PI: Anton Koekemoer This calibration proposal is the Cycle 12 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays {gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10073 Cycle: 12 Title: Earth Flats PI: Anton Koekemoer This proposal monitors flatfield stability. This proposal obtains sequences of Earth streak flats to construct high quality flat fields for the WFPC2 filter set. These flat fields will allow mapping of the OTA illumination pattern and will be used in conjuction with previous internal and external flats to generate new pipeline superflats. These Earth flats will complement the Earth flat data obtained during cycles 4-11. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10074 Cycle: 12 Title: WFPC2 Cycle 12 UV Earth Flats PI: Anton Koekemoer Monitor flat field stability. This proposal obtains sequences of earth streak flats to improve the quality of pipeline flat fields for the WFPC2 UV filter set. These Earth flats will complement the UV earth flat data obtained during cycles 8-11. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10075 Cycle: 12 Title: WFPC2 CYCLE 12 Intflat and Viflat Sweeps and Filter Rotation Anomaly Monitor PI: Anton Koekemoer Using intflat observations, this WFPC2 proposal is designed to monitor the pixel-to-pixel flatfield response and provide a linearity check. The intflat sequences, to be done once during the year, are similar to those from the Cycle 11 program 9597. The images will provide a backup database in the event of complete failure of the visflat lamp as well as allow monitoring of the gain ratios. The sweep is a complete set of internal flats, cycling through both shutter blades and both gains. The linearity test consists of a series of intflats in F555W, in each gain and each shutter. As in Cycle 11, we plan to continue to take extra visflat, intflat, and earthflat exposures to test the repeatability of filter wheel motions. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10076 Cycle: 12 Title: WFPC2 Cycle 12 CTE Monitor PI: Anton Koekemoer Monitor CTE changes during Cycle 12, including 2X2 binning characterization. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10077 Cycle: 12 Title: WFPC2 Cycle 12 Photometric Characterization PI: Inge Heyer Provide a check of the zeropoints and contamination rates in non-standard WFPC2 filters. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10078 Cycle: 12 Title: WFPC2 Cycle 12 Close-Out Photometric Cross-Calibration PI: Anton Koekemoer This proposal is aimed at providing photometric zeropoint cross-calibration between the commonly used WFPC2 photometric filter sets and those that will be used for ACS and WFC3. The proposal consists of observations of a set of standard stars, including the SDSS primary standard BD+17D4708 {F5} and two red standard stars, VB8 {an M7-dwarf} and 2M0036+18 {L3.5 dwarf}. For the red stars, medium and broad-band filters redward of F606W are calibrated, while for BD+17D4708 an extensive set of 22 medium and broad-band filters is used {from F185W to F1042M}. The intent is to observe these stars with as many filters as possible, to eventually allow cross-calibration of archival WFPC2 data with data from ACS, WFC3, SDSS and 2MASS. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10079 Cycle: 12 Title: Geometric distortion of F255W for WFPC2 Cycle 12 PI: Vera Kozhurina-Platais The goal of astrometric calibration of the HST WFPC2 is to obtain a coordinate system free of distortion down to the precision level of 1 mas. That precision is necessary for future astrometric work {e.g., on proper motions} involving a combination of the archival WFPC2 and recent ACS images. So far such a calibration has only been obtained for the wide bandpass F555W filter {Anderson and King, 2003}. Recently V. Kozhurina-Platais {ISR, 2003-002} has expanded the analysis of the geometric distortion of WFPC2 as a function of wavelength for two other broadband filters, {F814W and F300W}, and has also established the plate scale and skew parameters {non-perpendicularity of X and Y axes} for these filters. This study points to the importance of astrometric calibration at wavelengths shorter than ~400 nanometers. This proposal seeks observations in the FUV filter F255W of the Inner Calibration Field in the globular cluster omega Cen. It is expected that the amount of distortion in the F255W filter with respect to the F555W filter will be higher by 5% but this must be established from observations. A total of four astrometric calibrations in F255W {proposed here}, and F300W, F555, F814W {already completed} will allow us to interpolate such a calibration for any other filter from FUV to near infrared. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10080 Cycle: 12 Title: Wavelength Stability of Narrow Band and Linear Ramp Filters PI: James Rhoads Verify the mapping of wavelength as a function of CCD position on LRFs; check for changes in central wavelengths of narrow band filters. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10081 Cycle: 12 Title: Is the exoplanet HD209458b's exosphere in a blowoff state ? PI: Alfred Vidal-Madjar Using HST Lyman alpha observations, we have detected an extended tail shaped upper atmosphere around the extra-solar planet HD209458b. The Cycle 10 STIS G140M observations revealed an absorption of 15+/-4% of the stellar Lyman alpha emission line during the planetary transit in front of the star {Vidal-Madjar, et al. 2003}. This showed that HI evaporation is taking place within a highly extended upper atmosphere. Very recent studies on the evaporation mechanism are now indicating that instead of ``Jeans escape'' a more probable mechanism is complete atmospheric ``blowoff'' as suffered by the telluric planets in the early solar system. This mecanism could be directly tested with HST by searching for the escape of species slightly heavier than HI. It is easy to show that neither oxygen nor carbon would be detected with HST if only ``Jeans escape'' takes place while both species, under ``blowoff'' conditions, should reach the Roche limit of the planet and escape as hydrogen. If this is the case an absorption during transit of about 15% should be observed for both. Twelve orbits with the STIS G140L spectrograph will allow us to detect the presence of these species during three transits with a better than 5% accuracy, needed to detect an object of the size of the planetary Roche lobe. Simultaneously these observations will confirm and give more precision about the extention of the HI cometary like tail expected to occult the star well after the end of the visible transit. This proposed investigation is a unique opportunity to further study hot giant planets upper atmospheres, reveal the precise evaporation mechanism and give new constraints on the ``hot Jupiters'' lifetime. This could explain the lack of planets discovered so far at less than 0.04~AU from their star. We ask for HST observations under Director Discretionnary time to have access to the coming transits observable in the early fall of 2003. ------------------------------------------------------------------------------ Prop. Type: GO/PAR Category: ID: 10082 Cycle: 12 Title: WFII backup parallel archive proposal PI: James Rhoads This is a POMS test proposal designed to simulate scientific plans. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: SOLAR SYSTEM ID: 10083 Cycle: 12 Title: HST UV Images of Saturn's Aurora Coordinated with Cassini Solar Wind Measurements PI: John Clarke A key measurement goal of the Cassini mission to Saturn is to obtain simultaneous solar wind and auroral imaging measurements in a campaign scheduled for Jan. 2004. Cassini will measure the solar wind approaching Saturn continuously from 9 Jan. - 6 Feb., but not closer to Saturn due to competing spacecraft orientation constraints. The only system capable of imaging Saturn's aurora in early 2004 will be HST. In this community DD proposal we request the minimum HST time needed to support the Cassini mission during the solar wind campaign with UV images of Saturn's aurora. Saturn's magnetosphere is intermediate between the "closed" Jovian case with large internal sources of plasma and the Earth's magnetosphere which is open to solar wind interactions. Saturn's aurora has been shown to exhibit large temporal variations in brightness and morphology from Voyager and HST observations. Changes of auroral emitted power exceeding one order of magnitude, dawn brightenings, and latitudinal motions of the main oval have all been observed. Lacking knowledge of solar wind conditions near Saturn, it has not been possible to determine its role in Saturn's auroral processes, nor the mechanisms controlling the auroral precipitation. During Cassini's upcoming approach to Saturn there will be a unique opportunity to answer these questions. We propose to image one complete rotation of Saturn to determine the corotational and longitudinal dependences of the auroral activity. We will then image the active sector of Saturn once every two days for a total coverage of 26 days during the Cassini campaign to measure the upstream solar wind parameters. This is the minimum coverage needed to ensure observations of the aurora under solar wind pressure variations of more than a factor of two, based on the solar wind pressure variations measured by Voyager 2 near Saturn on the declining phase of solar activity. The team of proposers has carried out a similar coordinated observing campaign of Jupiter during the Cassini flyby, resulting in a set of papers and HST images on the cover of Nature on 28 February 2002. ------------------------------------------------------------------------------ Prop. Type: GO/PAR Category: ID: 10084 Cycle: 12 Title: WFII parallel archive proposal PI: James Rhoads This is the generic target version of the WFPC2 Archival Pure Parallel program. The program will be used to take paralell images of random areas of the sky, following the recommendations of the 2002 Parallels Working Group. ------------------------------------------------------------------------------ Prop. Type: ENG/STIS/P Category: ID: 10085 Cycle: 12 Title: STIS Pure Parallel Imaging Program: Cycle 12 PI: Paul Goudfrooij This is the default archival pure parallel program for STIS during cycle 12. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10086 Cycle: 12 Title: The Ultra Deep Field with ACS PI: Steven Beckwith The ACS Ultra Deep Field {UDF} is a survey carried out by using Director's Discretionary time. The main science driver are galaxy evolution and cosmology. The primary instrument is the Advanced Camera for Surveys but WFPC2 and NICMOS will also be used in parallel. The data will be made public. The UDF consists of a single ultra-deep field {410 orbits in total} within the CDF-S GOODS area. The survey will use four filters: F435W {55 orbits}, F606W {55 orbits}, F775W {150 orbits}, and F850LP {150 orbits}. The F435W {B} and F606W {V} exposures will be one magnitude deeper than the equivalent HDF filters. The F775W {I} exposure will be 1.5 magnitude deeper than the equivalent HDF exposure. The depth in F775W and F850LP is optimized for searching very red objects - like z=6 galaxies - at the detection limit of the F850LP image. The pointing will be RA{J2000}=3 32 40.0 and Decl.{J2000}=-27 48 00. These coordinates may change slightly due to guide star availability and implementation issues. We will attempt to include in the field both a spectroscopically confirmed z=5.8 galaxy and a spectroscopically confirmed type Ia SN at z=1.3. The pointing avoids the gaps with the lowest effective exposure on the Chandra ACIS image of CDFS. This basic structure of the survey represents a consensus recommendation of a Scientific Advisory Committee to the STScI Director Steven Beckwith. A local Working Group is looking in detail at the implementation of the survey. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10087 Cycle: 12 Title: STIS HITM2 Lamp Brightness Check PI: Linda Dressel We will measure the brightness of the HITM2 lamp at operating currents 3.8mA and 10mA in ACQ-type reference aperture exposures. We will check whether the 10mA setting can be used in the ACQ procedure without saturation. We will also take wavecals with HITM2 at 10mA at the grating/central wavelength settings most commonly used for cycle 12 science. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10088 Cycle: 12 Title: A Chandra HETGS & HST view of the Warm and Lukewarm absorbers in IRAS13349+2438 PI: Julia Lee We propose a 300~ks HETGS observation simultaneous with a 4--orbit HST {UV} observation to study the archetypal infrared quasar IRAS13349+2438. We will explore its enigmatic properties and search for signatures of embedded dust {implicated by the high extinction} in the warm absorber clouds of this object. We will plan to propose for simultaneous optical observations to be taken using the 6.5-m Magellan telescope {through the PI host institution}. The X-ray spectra will give unprecedented high- resolution information for this source necessary for probing in detail the physical properties, chemical compositions and velocities of the material surrounding the AGN. We will additionally assess the `unresolved transition array' {UTA} reported for this object, and search for and measure the neutral Fe L edge seen in a similarly reddened AGN. This will be complemented with simultaneous HST UV spectra to determine the continuum shape and to assess whether the UV/X-ray absorbers in this system are related. The Chandra data will also allow us to look for narrow features at >2 keV. Such a broad waveband study of this object will enable us to obtain a complete picture of the geometry and physics of the system, as well as the physical processes which are responsible for the variability in the absorber. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10089 Cycle: 12 Title: Hubble Heritage Image of the Light Echo around V838 Monocerotis PI: Keith Noll We will obtain a spectacular color image of the light echo around V838 Mon ------------------------------------------------------------------------------ Prop. Type: GO/PAR Category: ID: 10090 Cycle: 12 Title: WFII backup parallel archive proposal PI: James Rhoads This is a POMS test proposal designed to simulate scientific plans. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10091 Cycle: 12 Title: Soft X-ray Transient in Mira AB PI: Margarita Karovska Chandra Observations of Mira AB symbiotic-like system obtained in Dec. 2003 detected an unexpected bright soft source {<0.7 keV} in addition to the previously observed harder {1-4 keV} emission which has been attributed to the accretion disk around Mira B. The newly discovered soft X-ray source could indicate an instability in the accretion disk, an accretion related outburst in the system, or a flare-like activity in Mira A. We request DD time to carry out HST/STIS imaging and spectroscopy of Mira AB at UV wavelengths, where signatures of these processes are very likely to be found. Because of the likely transient nature of this phenomenon, timely HST observations are critical for determining the nature and the characteristics of the soft X-ray source and therefore we cannot wait for Cucle 13 observatios including TOO observations. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10092 Cycle: 13 Title: The COSMOS 2-Degree ACS Survey PI: Nicholas Scoville We will undertake a 2 square degree imaging survey {Cosmic Evolution Survey -- COSMOS} with ACS in the I {F814W} band of the VIMOS equatorial field. This wide field survey is essential to understand the interplay between Large Scale Structure {LSS} evolution and the formation of galaxies, dark matter and AGNs and is the one region of parameter space completely unexplored at present by HST. The equatorial field was selected for its accessibility to all ground-based telescopes and low IR background and because it will eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS instrument. The imaging will detect over 2 million objects with I> 27 mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and extremely red galaxies out to z ~ 5. COSMOS is the only HST project specifically designed to probe the formation and evolution of structures ranging from galaxies up to Coma-size clusters in the epoch of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The size of the largest structures necessitate the 2 degree field. Our team is committed to the assembly of several public ancillary datasets including the optical spectra, deep XMM and VLA imaging, ground-based optical/IR imaging, UV imaging from GALEX and IR data from SIRTF. Combining the full-spectrum multiwavelength imaging and spectroscopic coverage with ACS sub-kpc resolution, COSMOS will be Hubble's ultimate legacy for understanding the evolution of both the visible and dark universe. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10093 Cycle: 12 Title: Test of Filter Wheel Flight Software Update {ACS} PI: Colin Cox This test will be run following the installation of a flight software change which will position the filter wheels more accurately. It incorporates an ACS anneal and will substitute for one of the routine anneals that are carried out every four weeks. A series of internal flats will be taken with several filters. The exposures will be just long enough to obtain engineering data concerning the wheel positions. One external earth flat will also be taken to provide visual confirmation that the filter is correctly aligned. In the event of a problem being found, an operations request will be issued to revert to the original software. There are several requirements affecting timing and real-time contact. 1. Visit 1 must be scheduled to start within 12 hours of an SMS boundary. 2. Engineering telemetry contact must be available during visits 4, 5 and 6 3. An uplink opportunity must be available, at least 30 minutes after execution of the test, i.e. completion of visits 4, 5 and 6 {visit 7 should have several orbit gap from the last of 4, 5 and 6. 4. Visit 7 may not proceed, nor may any other ACS observation take place after the start of visit 1 until the uplink opportunity has occurred. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10094 Cycle: 13 Title: Mid-Ultraviolet Spectral Templates for Old Stellar Systems PI: Ruth Peterson We propose a three-year program to provide both observational and theoretical mid-ultraviolet {2300A -- 3100A} spectral templates for interpreting the age and metallicity of globular clusters and elliptical galaxies from spectra of their integrated light. The mid-UV is the region most directly influenced by stellar age, and is observed directly in optical and infrared studies of high-redshift quiescent systems. The reliability of age and metallicity determinations remains questionable until non-solar metallicities and abundance ratios are considered, and stars spanning the color-magnitude diagram are included, as we propose here. With archival HST STIS spectra we have improved the list of mid-UV atomic line parameters, then calculated spectra from first principles which match observed spectra of standard stars up to one- fourth solar metallicity. We will extend both observations and calculations to stars of solar metallicity and beyond, and to those in short-lived stages hotter than the main-sequence turnoff, stars not currently well-represented in empirical libraries. The necessary line-list improvements will come from new high-resolution mid-UV spectra of nine field stars. A key application of the results of this program will be to the old systems now being discovered as `Extremely Red Objects' at high redshifts. Reliable age-dating of these places constraints on the epoch when large structures first formed in the universe. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10095 Cycle: 12 Title: Hubble Heritage Observations of Deep Impact Target Comet Tempel-1 PI: Keith Noll This proposal observes Comet Tempel-1 near the time of Deep Impact, using the ACS-WFC, in filters F435W {3x340 sec} and F625W {1x100 sec and 2 x 340 sec}. ------------------------------------------------------------------------------ Prop. Type: ENG/STIS/P Category: ID: 10096 Cycle: 12 Title: STIS Pure Parallel Imaging Program: Cycle 12 PI: Paul Goudfrooij This is the default archival pure parallel program for STIS during cycle 12. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10097 Cycle: 12 Title: NICMOS Temperature Setpoint Darks PI: Bahram Mobasher NICMOS darks at different temperatures are needed to calibrate the software tool used to create synthetic darks. Synthetic darks are used during calibration. The temperatures of the NICMOS detectors will be adjusted by +0.5 to -1.0 K from the nominal operating temperature. Darks in each camera will be obtained at each of the temperature settings. At the end of the Proposal the NCS nominal setpoint temperature for the NICMOS detectors will be increased by 0.07 K for the cool season {routine seasonal adjustment}. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM AND CIRCUMSTELLAR MATTER ID: 10098 Cycle: 13 Title: Probing the nature of Type Ia SNe through HST astrometry PI: Pilar Ruiz-Lapuente Type Ia supernovae are of key importance in cosmology. Empirical relations allow their use as cosmological standard candles. The generally accepted picture is that the exploding star is a C+O white dwarf which accretes matter from a companion in a binary system. However, the nature of the companion is still unknown. It could either be another WD, or be a giant, subgiant, or main-sequence star. Calculations have shown that it is possible to distinguish among those possibilities by the effect that the supernova explosion has on the companion star. We propose to identify the companion star of the two historical well-known SNeIa through ACS imaging of the targets complemented by WFPC2 observations. A radial-velocity study of the stars in those two Galactic SNeIa has been done from ground-based facilities. To obtain the full motion vector of those stars, we plan to use ACS for high-resolution astrometry in two different epochs. That should allow to detect motion imparted during the explosion in the d ir ection perpendicular to the line of sight, down to a level of a few milliarcsecs/yr. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10099 Cycle: 13 Title: The Parallax of Geminga PI: Frederick Walter The distances to neutron stars are a fundamental parameter that impacts estimates of radii and luminosities, both of which have important ramifications for neutron star heating and cooling and for the equation of state of nuclear matter. A radius measured to 5% accuracy will provide useful astrophysical constraints on the equation of matter at nuclear densities. This requires an accurate measurment of the distance. Caraveo et al. have reported a distance to the isolated pulsar Geminga based on three WFPC2 images. We have not been able to reproduce that result. We request time with the ACS/WFC over two years to obtain 4 images in order to determine the parallax of Geminga. In addition to the general importance of understanding neutron star radii and luminosities, this will provide specific insights into the history of gamma ray pulsars in general, and of Geminga itself. We have obtained the first two images {cycle 12}; these two cycle 13 images will complete the program. ------------------------------------------------------------------------------ Prop. Type: GO Category: COLD STARS ID: 10100 Cycle: 13 Title: Tracking the Evolution of a Knotty, High- Speed Jet in the Carbon Star, V Hydrae PI: Raghvendra Sahai The carbon star V Hydrae is experiencing heavy mass loss as it undergoes the transition from AGB star to pre-planetary nebula. This is possibly the earliest object known in this brief phase. Molecular observations reveal that a bipolar nebula has been established even at this early stage. Using STIS on the HST, we have discovered a high-velocity {> 200 km/s} jet or blob of gas which was ejected only ~2 years ago from near the star. A second STIS observation 11 months later clearly showed both its proper motion and the fact that it is being strongly decelerated. We propose STIS monitoring of this remarkable event for an additional 3 years, in order to: 1} obtain a precise dynamical and cooling history of this blob, and 2} determine whether the ejection of such blobs is associated with, or perhaps phased with, the 530-day stellar period. This ejection event is likely to hold the key to understanding why initially spherical mass outflows adopt a bipolar geometry during the post-AGB phase of stellar evolution. We not only have the opportunity to look on as the circumstellar envelope is sculpted by this and perhaps other collimated mass ejections, but we also have an unprecedented chance to constrain the mechanism for mass ejection, and thereby help solve a long-standing puzzle. Finally, molecular line observations and our previous STIS H$lpha$ observations show that the V Hya system contains a prominent, central disk. We propose a follow-up study in H$lpha$ in order to better define the disk properties, and thereby to determine whether the disk plays a role in the collimation of the emerging blob. We will use the data to constrain hydrodynamical models of collimated jet interactions with the ambient circumstellar medium in V Hydrae, in order to set quantitative constraints on the physical properties of the blobby outflow. ------------------------------------------------------------------------------ Prop. Type: GO Category: COLD STARS ID: 10101 Cycle: 13 Title: The Region of the Hydrogen-Burning Limit in Omega Centauri and 47 Tucanae PI: Ivan King We propose a photometric study of the lower main sequences of Omega Cen and 47 Tuc, down to the region of the H-burning limit, which the deeper faintness limit of ACS will allow us to reach. For the faintest stars, proper-motion separation of cluster from field is essential; hence we include Cycle 13 observations. The resulting color--magnitude diagrams {CMDs} and luminosity functions {LFs} will allow study of stars in a mass regime and metallicity that have never been accessible before, and will serve as an important check on theories of the structure of low-mass stars. These are the 2nd-epoch observations. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10102 Cycle: 13 Title: Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons PI: Mark Showalter Last year, our Uranian ring and moon observing program {GO-9823} resulted in the discovery of two moons, S/2003 U 1 and S/2003 U 2. We imaged two additional small moons, Ophelia and S/1986 U 10, that had not been seen since the Voyager encounter of 1986. Furthermore, our data show faint arcs and clumps orbiting within the rings, which were not seen by Voyager and are completely unexpected. We employed several "tricks" of the HRC to achieve this remarkable senstivity; specifically, we used the CLEAR filter and oriented the images so that the planet, though vastly overexposed, did not interfere with the ring/moon region of interest to us. This allowed us to detect 25th-magnitude moons circling a 5th-magnitude planet. Now we propose to complete the task by carrying out a comprehensive survey of the system using the same techniques. Our goals are to recover the moons, better discern their orbital elements, and learn more about the dynamics of the ring clumps. In particular, we need to {1} understand the long-term stability of S/2003 U 2, which orbits perilously close to the larger moon Belinda; {2} complete our search for moons, which was only ~ 50% complete last year, and {3} better understand how the clumps and arcs within the ring system might relate to nearby "shepherding" moons, seen or unseen. This program is now a merger of two programs 10275 and 10102. The former is our new program, whereas the latter is the second year of our three-year program to study the light scattering properties of Uranus's rings as they approach their edge-on presentation in 2007. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10103 Cycle: 13 Title: FGS Astrometry of a Star Hosting an Extrasolar Planet: The Mass of Upsilon Andromedae d PI: George Benedict We propose observations with HST/FGS to determine the astrometric elements {perturbation orbit semimajor axis and inclination} produced by the outermost extra-solar planet orbiting the F8V star Upsilon Andromedae. These observations will permit us to determine the actual mass of the planet by providing the presently unknown sin i factor intrinsic to the radial velocity method which discovered this object. An inclination, i = 30degrees, within the range of one very low precision determination using reanalyzed HIPPARCOS intermediate data products, would produce the observed radial velocity amplitude, K = 66 ms with a companion mass of ~8 M_Jupiter. Such a mass would induce in Upsilon Andromedae a perturbation semi-major axis, Alpha = 0arcs0012, easily within the reach of HST/FGS fringe tracking astrometry. The proposed observations will yield a planetary mass, rather than, as previous investigations have done, only suggest a planetary mass companion. ------------------------------------------------------------------------------ Prop. Type: GO Category: COLD STARS ID: 10104 Cycle: 13 Title: Calibrating the Mass-Luminosity Relation at the End of the Main Sequence PI: Todd Henry We propose to use HST-FGS1R to calibrate the mass-luminosity relation {MLR} for stars less massive than 0.2 Msun, with special emphasis on objects near the stellar/brown dwarf border. Our goals are to determine M_V values to 0.05 magnitude, masses to 5 than double the number of objects with masses determined to be less than 0.20 Msun. This program uses the combination of HST-FGS3/FGS1R at optical wavelengths and ground-based infrared interferometry to examine nearby, subarcsecond binary systems. The high precision measurements with HST-FGS3/FGS1R {to 1 mas in the separations} for these faint targets {V = 10--15} simply cannot be equaled by any ground based technique. As a result of these measurements, we are deriving high quality luminosities and masses for the components in the observed systems, and characterizing their spectral energy distributions from 0.5 to 2.2 Mum. Several of the objects included have M < 0.1 Msun, placing them at the very end of the stellar main sequence. Three of the targets are brown dwarf candidates, including the current low mass record holder, GJ 1245C, with a mass of 0.062 +/- 0.004 Msun. The payoff of this proposal is high because all 10 of the systems selected have already been resolved with HST- FGS3/FGS1R during Cycles 5--10 and contain most of the reddest objects for which masses can be determined. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10105 Cycle: 13 Title: Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric Microlensing PI: Kailash Sahu We propose to determine the mass of the very cool white dwarf ER 8 through astrometric microlensing. We have predicted that ER 8 will pass very close to a 15th-mag background star in January 2006, with an impact parameter of less than 0.05 arcsec. As it passes in front, it will cause a deflection of the background star's image by >8 milliarcsec, an amount easily detectable with HST/FGS. The gravitational deflection angle depends only on the distances and relative positions of the stars, and on the mass of the white dwarf. Since the distances and positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of the white dwarf to high accuracy {<5%}. Unlike all other stellar mass determinations, this technique works for single stars {but only if they are nearby and of sufficient mass}. The mass of ER 8 is of special interest because it is a member of the Galactic halo, and appears to be the oldest known field white dwarf. This object can thus set a lower limit on the age of the Galactic halo, but since white-dwarf cooling rates depend on their masses, the mass is a necessary ingredient in the age determination. As a byproduct, we will obtain an accurate parallax for ER 8, and thus its luminosity and {from its effective temperature} its radius. Such quantities are at present rather poorly known for the coolest white dwarfs, and will provide strong constraints on white-dwarf physics. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10106 Cycle: 13 Title: An Astrometric Calibration of the Cepheid Period-Luminosity Relation PI: George Benedict We propose to measure the parallaxes of 10 Galactic Cepheid variables. When these parallaxes {with 1-sigma precisions of 10% or better} are added to our recent HST FGS parallax determination of delta Cep {Benedict et al 2002}, we anticipate determining the Period-Luminosity relation zero point with a 0.03 mag precision. In addition to permitting the test of assumptions that enter into other Cepheid distance determination techniques, this calibration will reintroduce Galactic Cepheids as a fundamental step in the extragalactic distance scale ladder. A Period-Luminosity relation derived from solar metallicity Cepheids can be applied directly to extragalactic solar metallicity Cepheids, removing the need to bridge with the Large Magellanic Cloud and its associated metallicity complications. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10107 Cycle: 13 Title: The Masses of the O-type Binary 15 Monocerotis PI: Douglas Gies The O-type star 15 Mon {HD 47839} was recently discovered to be an astrometric and spectroscopic binary with a period of 25 years; it is the first known O-star system to bridge the observational gap between the period regimes normally probed by these techniques. An analysis of both the radial velocity curve and astrometric orbit yields the masses of the components and distance to the system. Continuing radial velocity and HST/FGS astrometric measurements will lead to a definitive orbit and yield key information about the masses of O-type stars. FGS TRANS mode measurements of separation, position angle, and magnitude difference {begun in Cycle 5} are needed to link existing speckle observations and anticipated observations with the CHARA Array optical interferometer. In addition, field astrometry measurements {FGS POS mode} will provide the proper motion, parallax, and the binary motion around the center of mass. The POS data will provide an accurate estimate of the mass ratio and an improved estimate of distance, and taken together with the spectroscopic and astrometric orbital data, we will obtain masses for both components accurate to a few percent. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10108 Cycle: 13 Title: Dynamical Masses and Radii of Four White Dwarf Stars PI: Edmund Nelan The cool white dwarf stars WD1639+153 and WD1818+126 were recently resolved by HST FGS1r to be double degenerate binary systems with projected separations of 112 mas and 174 mas respectively. At a distance of less than 50 pc they may both have periods shorter than about 20 years, making them ideal candidates for follow up studies for dynamical mass determinations. This will increase the number of white dwarfs with dynamical mass measurements from the current 4 up to 8. Continued observations of these white dwarfs along with nearby field stars with the FGS will accuractely determine the orbital elements and parallax of each system. The mass and radius of all four white dwarfs can be determined to an unprecedented 1%, making it possible to test and calibrate the theoretical white dwarf mass radius relation at the cool end of the cooling curve for the DA and DC subclasses. Since the components of the binary are coeval, once the mass and radius, and hence the cooling age of each star is known, it will be possible to estimate the relation between the initial mass and final mass for all four white dwarfs. We are requesting a total of 4 HST orbits per year for the next three cycles to initiate the process that will result in a determination of the mass and radius of the four white dwarfs. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10109 Cycle: 13 Title: The Distance and Mass of the Neutrino-Luminous White Dwarf PG 0122+200 PI: M. Sean O'Brien PG 0122+200 is a pulsating hot white dwarf that is believed to radiate more energy as neutrinos than it does as photons. We propose to measure with FGS the trigonometric parallax of PG 0122+200 and thereby determine its distance, luminosity, and mass. Ongoing investigations from the ground will infer the neutrino luminosity through its effect on the pulsation periods, thus testing standard and non-standard lepton theory, but the stellar mass must first be known. The pulsation spectrum of PG 0122+200 admits two alternative seismological interpretations, each implying a different mass, luminosity, and distance. Measurement of an accurate distance will resolve the matter once and for all and precisely determine the stellar mass. This project represents the first test of lepton physics in dense {log rho = 6} plasma and is relevant to the many areas of stellar physics in which neutrino interactions are important, including recent theories intended to solve the solar-neutrino problem. ------------------------------------------------------------------------------ Prop. Type: GO Category: COLD STARS ID: 10110 Cycle: 13 Title: Parallaxes of Extreme Halo Subgiants: Calibrating Globular Cluster Distances and the Ages of the Oldest Stars PI: Don Vandenberg The ages of the oldest stars are a key constraint on the evolution of our Galaxy, the history of star formation, and cosmological models. These ages are usually determined from globular clusters. However, it is alternatively possible to determine ages of extreme Population II subgiants in the solar neighborhood based on trigonometric parallaxes, without any recourse to clusters. This approach completely avoids the vexing issues of cluster distances, reddenings, and chemical compositions. There are 3 known nearby, extremely metal-deficient Pop II subgiants with Hipparcos parallax errors of 6-11% which are available for such age determinations. At present, based on the latest isochrones, the derived ages of these stars {HD 84937, HD 132475, and HD 140283} are all close to 14 Gyr, uncomfortably close to or higher than current estimates of the age of the universe. However, the errors in the Hipparcos parallaxes imply uncertainties of at least 2 Gyr in the ages of the 3 stars. We propose to measure parallaxes of these three Pop II subgiants using HST's Fine Guidance Sensor 1R. We expect to reduce the Hipparcos parallax error bars by factors of 5-6, providing the most stringent test yet of current theoretical stellar models of Pop II stars and pushing the age uncertainties to below 0.5 Gyr. These data will also provide a major new constraint on the distance scale of globular clusters, with wide implications for stellar evolution and the calibration of Pop II standard candles. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10111 Cycle: 13 Title: Sakurai's Novalike Object: Real-Time Monitoring of a Stellar Thermal Pulse PI: Howard Bond This is a continuation of a program carried out in Cycles 7--10. Sakurai's Object {V4334 Sgr} presents a ``once-in-a-lifetime'' opportunity for real-time observations of a star undergoing a final helium thermal pulse. The star rose from obscurity to become an 11th-magnitude ``born-again'' hydrogen-deficient red giant in 1995-96, and currently it is undergoing episodes of atmospheric dust formation. If it follows the pattern that the similar object V605 Aql took early in the 20th century, it will soon begin evolving back to high temperature. During the subsequent few years, it will begin to {re}-ionize its large, faint, old planetary nebula as well as the new ejecta, and we should be able to witness the re-establishment and evolution of a fast stellar wind as the effective temperature increases. When the star does begin to heat up, we will initiate Target-of-Opportunity STIS observations to monitor the star's spectroscopic development in the UV at regular intervals, continuing over the next 3 Cycles. We will also use ACS/HRC twice over the next 3 years to continue our monitoring of the expansion of the ejecta and to determine the star's proper motion. In combination with ground-based monitoring {optical, IR, and mm}, we will thus produce the first detailed case study of a thermal pulse, as the star re-traces its evolution across the HR diagram from the AGB back to the hot planetary-nebula-nucleus phase. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10112 Cycle: 13 Title: HST Observations of Astrophysically Important Visual Binaries PI: Howard Bond This is a continuation of a project begun in Cycle 7 and continued up through Cycle 11. The program consists of annual or biannual WFPC2 or FGS observations of three visual binary stars that will ultimately yield fundamental astrophysical results, once their orbits and masses are determined. Our targets are the following: {1} Procyon {P = 41 yr}, for which our first WFPC2 images yielded an extremely accurate angular separation of the bright F star and its much fainter white-dwarf companion. Combined with ground-based astrometry of the bright star, our observation significantly revised downward the derived masses, and brought Procyon A into excellent agreement with theoretical evolutionary tracks for the first time. With the continued monitoring proposed here, we will obtain masses to an accuracy of better than 1%, providing a testbed for theories of both Sun-like stars and white dwarfs. {2} G 107-70, a close double white dwarf {P = 19 yr} that promises to add two accurate masses to the tiny handful of white-dwarf masses that are directly known from dynamical measurements. {3} Mu Cas {P = 21 yr}, a famous metal-deficient G dwarf for which accurate masses will lead to the stars' helium contents, with cosmological implications. ------------------------------------------------------------------------------ Prop. Type: GO Category: COLD STARS ID: 10113 Cycle: 13 Title: Trigonometric Calibration of the Period- Luminosity Relations for Fundamental and First-Overtone Galactic Cepheids PI: Howard Bond Cepheids are the primary distance indicators for the extragalactic distance scale and the Hubble constant. The Hubble Constant Key Project set the zero-point for their Cepheid distance scale by adopting a distance to the LMC, averaged over a variety of techniques. However, different methods give an LMC distance modulus ranging from 18.1 to 18.8, and the uncertainty in the Cepheid zero-point is now the largest contributor to the error budget for H_0. Moreover, the low metallicity of the LMC raises additional concerns, since the PL relation probably depends on metallicity. The zero-point can be determined from Hipparcos parallaxes of Galactic Cepheids out to several hundred parsecs, but with a typical parallax error of 0.5-1 mas, the Hipparcos error bars are uncomfortably large for this demanding application. By contrast, HST's FGS1R interferometer can achieve astrometric accuracy of 0.2 mas. We propose to use FGS1R to determine trigonometric parallaxes for a sample of 9 nearby Cepheids, including both fundamental {F} and first-overtone {FO} pulsators. We show that the improvement in the PL relations for F and FO Cepheids will be dramatic. We will determine the PL slopes from our nearby solar- metallicity sample alone, without recourse to nearby galaxies and the issue of [Fe/H] dependence. The zero-point will be determined robustly to about 0.05 mag, based on accurate, purely geometrical measurements. All of this can be achieved in the next few years with HST, without having to wait for the technically demanding and risky SIM and GAIA missions well into the next decade. ------------------------------------------------------------------------------ Prop. Type: GO Category: COOL STARS ID: 10114 Cycle: 13 Title: Lyman_alpha FUV observations of the Sun in time and effects on planetary atmospheres PI: Edward Guinan The chromospheric H I Ly_alpha 1215.6 feature is the dominant source of short-wave emission in the Sun and solar-type stars, contributing about 80-90% of the total FUV flux and 30-60% of the total flux between 1 and 1500 A. Also, this important chromospheric line is the major cooling channel for cool star atmospheres. Accurate Ly_alpha fluxes are the only missing element of our ongoing "Sun in Time" program. This program studies a sample of single G0-5 V stars with well-known physical properties that serve as proxies for the Sun {and solar-mass stars} over their main sequence lifetimes. One of the major goals of the program is the determination of the spectral irradiance of the early Sun. Our analyses indicate that the strong XUV emissions of the young Sun have played a crucial role in the developing planetary system. In particular, the expected strong Ly_alpha line flux may have greatly influenced the photoionization, photochemical evolution and possible erosion of planetary atmospheres, as well as played a role in the origin and development of life on Earth. The "Sun in Time" data can also be applied to investigate the atmospheric loss of exoplanets around solar-type stars resulting from XUV heating, which can eventually lead to the evaporation of "hot Jupiters". We propose to use HST/STIS-MAMA/E140M to determine accurate FUV and Ly-alpha fluxes and irradiances for 4 representative solar proxies with ages from 130 Myr to 6.7 Gyr. It is only with HST's high-resolution UV spectroscopy {to correct for ISM absorption} and the small aperture {to eliminate geocoronal emission} that the stellar Ly-alpha profile can be reliably modeled and its flux measured. The proposed study is of capital importance in reconstructing the evolutionary histories of exoplanets already known and additional planets that missions such as COROT, Kepler, SIM, and Darwin/TPF will discover in the coming years. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10115 Cycle: 13 Title: Rotation of Comet Tempel 1 PI: Michael A'Hearn We propose to accurately determine the rotational period of comet Tempel 1. This is crucial for enabling all of the science associated with the Deep Impact mission. It will also, in combination with ground-based data already on hand and images to be obtained from Deep Impact, provide the best dataset ever for investigating whether excited state rotation exists in any comet other than Halley. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10116 Cycle: 13 Title: Towards an Accurate Calibration of the Galactic Cepheid P-L Zero Point PI: Edward Guinan The young open cluster NGC 7790 is unique and astrophysically important because it contains three classical Cepheid variables {CF Cas, CE Cas A, and CE Cas B}. If the distance of NGC 7790 were known with certainty, these Cepheids would define the zero point for the galactic Cepheid Period-Luminosity {P-L} relationship. By a stroke of good luck, NGC 7790 also contains a 10th-mag eclipsing binary located near the turnoff of the main-sequence of the color-magnitude diagram of the cluster. This important eclipsing binary has been little studied until now and contains two B1IV-V+B3V stars with an orbital period of P=6.005 days. With HST we propose to secure the accurate distance and reddening of QX Cas {and thus of the Cepheids} by using eclipsing binaries as precise standard candles, as we have demonstrated in our work on the Large Magellanic Cloud. With absolute radii, temperatures, and luminosities of the stars known from ground-based and HST observations, the method is essentially geometric and free from many of the uncertainties that plague other less direct methods. Light and radial velocity curve data will be combined with the proposed HST/STIS spectrophotometry {1150-8000 A} to determine the physical properties of the eclipsing binary and thus to secure an accurate distance and reddening for NGC 7790. The determination of the stars' temperatures, reddenings and chemical abundances, and therefore the cluster's distance, with the necessary accuracy can only be accomplished with HST. According to our previous experience, we expect a resulting distance determination with an accuracy of about 2-3%. HST/STIS spectrophotometry will be carried out also for the three Cepheids to determine their properties and individual reddenings. Thus, the proposed HST observations could help eliminate the current nagging uncertainty of the galactic Cepheid zero point and provide the key for a firm calibration of the P-L relationship. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: AGN/QUASARS ID: 10117 Cycle: 13 Title: The Co-Evolution of Star Formation and Powerful Radio Activity in Galaxies PI: Christopher O'Dea We will carry out a STIS/NUV-MAMA snapshot imaging survey of the most compact powerful radio galaxies, the Gigahertz Peaked Spectrum {GPS} sources and Compact Steep Spectrum {CSS} sources. These objects are as powerful as the large radio doubles but are much smaller {and younger} and are crucial to our understanding not only of how radio-loud active galactic nuclei {AGN} form and evolve, but also what role they play in the evolution of galaxies. A very direct and robust way to address these issues is by high resolution imaging of the host galaxies of these sources in the UV. This has never been done before for a sample of these very compact sources, since previous HST/UV imaging programs have focussed on the larger radio galaxies. The UV emission can provide crucial information about any recent star formation that may have occurred as a result of ongoing accretion, mergers, interactions, or triggering by the radio source. By comparing the starburst properties of GPS, CSS, and large scale radio sources, we will be able to constrain the evolution of massive star formation as a function of the relative age of the radio source. {Note, due to the failure of STIS, these observations will be carried out using the ACS/HRC}. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10118 Cycle: 13 Title: Imaging the Chemical Distribution in Type Ia SN Ejecta PI: Robert Fesen We know Type Ia supernovae are thermonuclear explosions of CO white dwarfs, but we don't know the specifics of how the nuclear burning process proceeds from the core outward once it starts. The thermonuclear instability is thought to start off as a subsonic, turbulent deflagration or burning wave but then, at some point, may transition into a blast or detonation wave. In such "delayed detonation" models, differences between normal and subluminous Type Ia SNe reflect differences in the amount of burning that has occurred in the pre-detonation phase. More burning helps to pre-expand the WD before passage of the detontation wave, which then results in different final element abundances and internal Fe-rich ejecta structure. Directly imaging the 2-D chemical distribution of ejecta from a Type Ia SN is actually possible in the case of the subluminous Type Ia SN 1885, which occurred on the near-side of M31's central bulge. This 119 year old remnant is visible -- from its core to its outer edge -- via strong optical/UV Ca and Fe line absorptions. Remarkably, the SNR appears to still be in a nearly free expansion phase, meaning that the elemental stratification seen present today accurately reflects SN Ia explosive nucleosynthesis physics. We propose to obtain ACS WFC/HRC images of SN 1885 in order to take advantage of this extraordinary situation: Having a young, nearby Type Ia SN remnant visible in silhouette against a galaxy-size light table. These unique observations will reveal a SN Ia's Ca and Fe ejecta distribution, density structure, sphericity, and ionization state as a function of expansion velocity, thereby confronting various SN Ia models with detailed ejecta stratification and expansion velocity maps. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10119 Cycle: 13 Title: Solving the Mystery of the Short-Hard Gamma-Ray Bursts PI: Derek Fox Seven years after the afterglow detections that revolutionized studies of the long-soft gamma-ray bursts, not even one afterglow of a short-hard GRB has been seen, and the nature of these events has become one of the most important problems in GRB research. The forthcoming Swift satellite will report few-arcsecond localizations for short-hard bursts in minutes, however, enabling prompt, deep optical afterglow searches for the first time. Discovery and observation of the first short-hard optical afterglows will answer most of the critical questions about these events: What are their distances and energies? Do they occur in distant galaxies, and if so, in which regions of those galaxies? Are they the result of collimated or quasi-spherical explosions? In combination with an extensive rapid-response ground-based campaign, we propose to make the critical high-sensitivity HST TOO observations that will allow us to answer these questions. If theorists are correct in attributing the short-hard bursts to binary neutron star coalescence events, then the short-hard bursts are signposts to the primary targeted source population for ground-based gravitational-wave detectors, and short-hard burst studies will have a vital role to play in guiding their observations. ------------------------------------------------------------------------------ Prop. Type: GTO/AST Category: ID: 1012 Cycle: 0 Title: HIGH-RESOLUTION SURFACE PHOTOMETRY OF NGC 4314 : CYCLE 0 PI: William Jefferys We propose to obtain ST WF/PC surface photometry of NGC 4314. NGC 4314 exhibits anomalous nuclear activity indicative of on-going star formation. Multicolor surface photometry with 0.1 to 0.4 arcsec resolution will afford an opportunity to explore the global interrelationships between gas clouds, dust, star formation, and stellar populations with detail never before obtained. The expected maximum resolution for for NGC 4314 is 10 parsecs. While most of the data will be secured after the refurb mission with WFPC II, these early I-band exposures will allow studies of structures. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10120 Cycle: 13 Title: The Formation Histories and Dynamical Roles of X-ray Binaries in Globular Clusters PI: Scott Anderson Close binaries are fundamental to the dynamical stability and evolution of globular clusters, but large populations have been extremely difficult to identify. Chandra X-ray images provide a revolutionary resource, revealing a few to dozens of low-luminosity X-ray sources in every cluster deeply examined; our own Chandra programs uniformly study these ubiquitous X-ray sources {close binaries and their progeny} in 11 clusters. However, definitive understanding of the nature of the various X-ray subpopulations requires the identification of optical counterparts, and HST is the demonstrated key in these crowded environments. We thus propose a proven, efficient, and uniform, HST multicolor imaging program for optical identifications in 6 of our clusters with Chandra data on-hand, but which lack adequate optical images in the HST archive. The proposed ACS images will permit statistical classifications into the various subtypes: CVs, qLMXBs, BY Dra's/RS CVn's {and MSPs}. A unique aspect of our program is that our clusters span a range of physical properties such as central concentration, cluster size, and mass--essential ingredients in the formation, evolution, and dynamical roles of cluster binaries. Exploiting this range of properties, we have identified a relation that provides the first compelling link between the number of X-ray sources and the predicted stellar encounter frequency in globular cluster cores. But further progress in understanding the details implicit in this relationship {e.g., whether CVs and qLMXBs formed primarily via stellar encounters, while BY Dra's/RS CVn's are mainly primordial binaries} demands uniform optical identifications for multiple clusters, spanning the full range physical properties. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10121 Cycle: 13 Title: The Core Dynamics of the Dense Globular Cluster NGC 6752 PI: Charles Bailyn NGC 6752 is one of the best-studied dense globular clusters, and a wide variety of intriguing and anomalous results have been obtained. We propose ACS imaging of the core of this cluster. This will increase the accuracy of our previous internal proper motion measurements by almost an order of magnitude, providing an unprecedented probe of the central potential. The data will also greatly increase the radial extent of previous work on the binary frequency and luminosity function of this cluster. Together, the data will provide a new level of constraints on the dynamics of a dense globular cluster. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10122 Cycle: 13 Title: Accretion in the closest binary systems known PI: Danny Steeghs Recently, three variable stars have been identified as likely accreting binary systems with ultra-short orbital periods. Optical and X-ray observations have revealed periodicities of 5-10 minutes, making them the closest binaries known as well as strong sources of gravitational wave emission. Such short-period accreting binaries form the cornerstone to our understanding of binary formation and evolution, in particular of the large double white dwarf population in our galaxy, a candidate progenitor population for Type Ia supernovae. We propose to obtain the first UV observations of these objects using STIS in order to {i} determine the temperature of the primary and the composition of their donor stars, {ii} correlate the UV variability with other wavebands and determine if the periods are indeed orbital, {iii} look for dynamical signatures of direct-impact accretion that is expected to govern the survival rate of double white dwarfs. These UV observations are essential in order to unequivocally determine whether these are indeed the most compact binaries known. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10123 Cycle: 13 Title: Microarcsecond Imaging of a Gravitationally Lensed QSO: 2237+0305 PI: Rachel Webster The microarcsecond scale structure of the central region of the gravitationally lensed quasar, 2237+0305, can be determined from its wavelength dependent lightcurve if viewed during a microlensing event. We are monitoring the QSO from the ground at regular intervals to ascertain the onset of a microlensing event. STIS spectra will then be taken and compared with the spectra taken after the event. As the microlensing event occurs, we will measure wavelength- dependent changes in the continuum, and also the variations in lines with different ionizations. Thus we will use microlensing to directly probe the structure of the source QSO on microarcsecond scales -- a factor of ten smaller than those measured by indirect techniques such as reverberation mapping. An already approved CHANDRA Cycle 3 GO program will provide complementary X-ray data, thus greatly increasing the wavelength range over which we hope to probe the quasar's inner structure. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10124 Cycle: 13 Title: Physical Processes in Orion's Veil: A High Resolution UV Absorption Study of the Line of Sight towards the Trapezium PI: Gary Ferland Star formation is governed by a complex interplay among magnetic, thermal, turbulent and gravitational energies. Of these, magnetic energies are the most difficult to measure. Yet magnetic energies are crucial to the evolution of molecular clouds if they are comparable to other energies. Unfortunately, magnetic field strength measurements are sparse. Moreover, detailed field strength maps exist in only one region of the ISM, the veil of neutral material in front of the Orion Nebula. From the Zeeman effect in 21cm HI absorption lines, we have accurate maps of the line-of-sight field strength in two independent velocity components of the veil. Therefore, the veil presents a unique laboratory for study of magnetic effects in star forming regions. We have recently combined archival UV absorption line data with photoionization models to estimate the veil's density, temperature and level of ionization. On this basis, we infer that magnetic energies far exceed turbulent and thermal energies in at least one HI velocity component. This component is magnetically unique. All other data about star forming regions suggest equipartition between magnetic and turbulent energies. Our analysis of physical conditions in Orion's veil suffers from an important limitation. Existing UV absorption line data have insufficient spectral resolution to separate the two HI velocity components. Therefore, our models reflect average conditions in the two components. Yet actual conditions are likely to be quite different since one component must lie closer to the source of ionization. We propose to use STIS to obtain high resolution UV spectra of Theta 1 Ori B. These data will allow us to model the two velocity components separately. We can then estimate magnetic and other energies in the two components. We will determine if the apparent magnetic uniqueness of one component applies to both, and we will estimate the distances of each component from the ionizing stars. This study will provide the most comprehensive information obtainable about the role of magnetic effects in a star forming region. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10125 Cycle: 13 Title: Where is the Wind in 1H0707-495? PI: Karen Leighly We propose three observations using HST STIS of the narrow-line Seyfert 1 galaxy 1H 0707-495 to be coordinated with already-approved deep exposures using FUSE. A previous HST observation of 1H 0707-495 revealed strongly blueshifted high-ionization lines, suggesting an origin in an outflowing wind. Detailed photoionization modeling reveals that the wind line fluxes and ratios are consistent with two solutions: a high-density, high-column solution, originating close to the central engine, and a low-density, low-column solution, located much further out. These two locations, interestingly, correspond to those predicted by two different physical models for winds in AGNs. We can differentiate between these models by observing emission line variability on two time scales, and examining relative variability of OVI obtained by FUSE and CIV and other lines obtained by HST. We will also look for profile variability, constrain velocity ionization stratification through a detailed study of the profiles, and investigate metallicity, which has been suggested to be high in NLS1s. This program, requiring only a modest amount of time, is expected to make significant contributions to our understanding of outflows in AGN, and the structure, origin and metallicity of the broad-line region. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10126 Cycle: 13 Title: The 3-D Shape of the SMC: Is It Tidally Distorted? PI: Edward Olszewski We propose to exploit the exceptional spatial resolution of HST to definitively show whether the SMC is tidally elongated along the line-of-sight, and therefore the status of the Milky Way's interaction/destruction of the Magellanic Clouds. We use BVI ACS images of several crowded SMC fields in the region predicted by models of the orbit and tidal evolution of the Magellanic Clouds {and by observations of Cepheids} to have a large depth. We exploit the red clump feature {and the rarer true horizontal branch} to derive the depth. Specifically, we will observe six fields along the predicted region of maximum distance gradient of the SMC, along with two ACS fields and several WFPC2 fields in the archives, to map out the depth of the SMC in this region. We are searching for substructure, such as a tidal tail, that may be present. Crowding in this region of the SMC is so severe that this project cannot be done from the ground. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10127 Cycle: 13 Title: Imaging a protocluster at z=3.1: Effects of environment and evolution on galaxy populations in the early universe PI: George Miley We propose imaging a rich protocluster, 0316-26 at z = 3.13, with 31 confirmed Lya cluster members. The bright radio galaxy host is identified with the progenitor of the dominant cluster galaxy. Because its redshift places Lya into an ACS narrow-band filter, the protocluster provides a unique laboratory for studying galaxies at a crucial epoch in the evolution of the Universe. We shall {i} measure and compare sizes, morphologies and colors of galaxies from populations detected using 4 different selection techniques {Lyman and 4000A breaks, Lya and [OIII] excesses}, {ii} study effects of an overdense environment by comparing the properties of protocluster galaxies with z~3 field galaxies from GOODS, {iii} study effects of evolution by relating our data to observations of similar protocluster/cluster targets at redshifts z = 4.1, 2.2, and 1.2, and {iv} constrain the formation of the most massive cluster galaxies by investigating the spatial distribution, Lya equivalent widths and other properties within the 5" radio galaxy host. The ultimate aim is to disentangle the history of structure development and stellar evolution for rich clusters of galaxies. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10128 Cycle: 13 Title: Probing the Formation & Evolution of M31's Outer Disk and Halo, Part II PI: Annette Ferguson Over the past several years, our group has conducted a large panoramic ground-based imaging survey of resolved luminous stars in M31 using the INT Wide-Field Camera. Our now complete survey covers 40 square degrees around M31, extending to a major axis distance of ~60 kpc. This survey has led to the discovery of numerous spatial density and/or colour {metallicity?} variations within the M31 halo and outer disk, and interim results motivated a successful Cycle 11 HST/ACS program to obtain deep colour-magnitude diagrams for six regions exhibiting the most prominent stellar substructure known at that time, including the giant stellar stream and the clump of stars near the anomolous cluster, G1. The present proposal requests time to augment our Cycle 11 program with observations of two new features, a very low surface brightness fragment lying 3 degrees north-east of center and a high surface brightness spur of emission in the south-western half of the galaxy, which we have discovered since 2001. Deep colour-magnitude diagrams reaching 2-3 magnitudes below the horizontal branch will be constructed, allowing detailed characterization of the luminous evolved stellar populations via the red giant metallicity distribution, the luminous asymptotic giant branch, the horizontal branch morphology and the red clump, as well as the detection of a main-sequence that may be present from any younger component. Together the Cycle 11 and 13 pointings target all prominent stellar substructure known to exist within 60 kpc of M31. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10129 Cycle: 13 Title: Resolving Globular Clusters in NGC 1399 PI: Thomas Puzia We intend to use the ACS/WFC to measure structural parameters {half light radius, King core radius and concentration parameter} of individual globular clusters {GCs} in NGC 1399. Very little is known about structural parameters of globular clusters as a function of radius outside the Local Group. The proposed observations, arranged in a 3x3 ACS mosaic, will allow us to perform the first detailed wide-field study of structural parameters of globular clusters in a giant elliptical galaxy. In particular we will: 1} study the size-galactocentric distance relation of globular clusters out to ~55 kpc {~1.6 eff. radius of the GCS} and determine whether the observed differences in sizes between metal-rich and metal-poor globular cluster in early-type galaxies are primordial and thereby reflect fundamental differences in formation, or are due to projection effects; 2} match the GC position observed with HST/ACS with X-ray binaries identified over the full Chandra field, and use the above sizes to constrain physical models for X-ray binary formation in GCs. 3} The wealth of ground-based data available for this system {photometry+spectroscopy}, will allow us to correlate the structural properties with other GC properties, such as their chemical composition, luminosity, etc. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: STELLAR POPULATIONS ID: 10130 Cycle: 13 Title: Systemic Proper Motions of the Magellanic Clouds from Astrometry with ACS: II. Second Epoch Images PI: Charles Alcock We request second epoch observations with ACS of Magellanic Cloud fields centered on the 40 quasars in the LMC and SMC for which we have first epoch Cycle 11 data. The new data will determine the systemic proper motion of the Clouds. An extensive astrometric analysis of the first epoch data shows that follow-up observations with a two year baseline will allow us to measure the proper motion of the clouds to within 0.022 mas/year in each of the two orthogonal directions {assuming that we can image 25 quasars, i.e., with a realistic Snapshot Program completion rate}. The best weighted combination of all previous measurements has a seven times larger error than what we expect. We will determine the proper motion of the clouds with 2% accuracy. When combined with HI data for the Magellanic Stream this will constrain both the mass distribution in the Galactic Halo and theoretical models for the origin of the Magellanic Stream. Previous measurements are too crude for such constraints. Our data will provide by far the most accurate proper motion measurement for any Milky Way satellite. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10131 Cycle: 13 Title: Determining the Origin of Virgo's Intracluster Stars PI: Robin Ciardullo Intracluster stars constitute about 20% of the total stellar population of a typical galaxy cluster, and their existence provides a vital clue for our understanding of cluster formation and evolution. However, to exploit their probative value, we need to know their origins: are they the remnants of dwarf galaxies, long since destroyed by the cluster potential, or have the stars been harassed from their parent galaxies at recent epochs? To answer this question, we propose to use the Wide-Field Channel of ACS to make an I, {V-I} color-magnitude diagram of Virgo's intracluster stars. From the position and morphology of the population's red giant branch, we will be able to determine the metallicity distribution function of the stars, and thereby determine their likely origin and ejection mechanisms. Only HST with the ACS has the sensitivity and resolution to perform this fundamental measurement. This program has two options. Option one uses conventional methods of cluster photometry and requires 37 orbits of exposure time. Option two involves a novel analysis technique, which promises to achieve most of the same science in two-thirds the time {23 orbits}. We describe this alternative method of analysis and demonstrate its use via simulations. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: QUASAR ABSORPTION LINES/IGM ID: 10132 Cycle: 13 Title: UV Confirmation of New Quasar Sightlines Suitable for the Study of Intergalactic Helium PI: Scott Anderson The reionization of intergalactic helium is thought to have occurred between redshifts of about 3 and 4. The study of HeII Lyman-alpha absorption towards a half-dozen quasars at 2.72.9 SDSS quasars, but with special emphasis on extending helium studies to the highest redshift sightlines. Our proposed approach has already proven successful, and additional sightlines will enable follow-up spectal observations to measure the spectrum and evolution of the ionizing background radiation, the density of intergalactic baryons, and the epoch of reionization of the IGM. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10133 Cycle: 13 Title: HST / Chandra Monitoring of a Dramatic Flare in the M87 Jet PI: John Biretta As the nearest galaxy with an optical jet, M87 affords an unparalleled opportunity to study extragalactic jet phenomena at the highest resolution. During 2002, HST and Chandra monitoring of the M87 jet detected a dramatic flare in knot HST-1 located ~1" from the nucleus. As of late 2003 its brightness has increased twenty-fold in the optical band, and continues to increase sharply; the X-rays show a similarly dramatic outburst. In both bands HST-1 now greatly exceeds the nucleus in brightness. To our knowledge this is the first incidence of an optical or X-ray outburst from a jet region which is spatially distinct from the core source; this presents an unprecedented opportunity to study the processes responsible for non-thermal variability and the X-ray emission. We propose seven epochs of HST/STIS monitoring during Cycle 13, as well as seven epochs of Chandra/ACIS observation {5ksec each}. We also include a brief HRC/ACS observations that will be used to gather spectral information and map the magnetic field structure. This monitoring is continued into Cycles 14 and 15. The results of this investigation are of key importance not only for understanding the nature of the X-ray emission of the M87 jet, but also for understanding flares in blazar jets, which are highly variable, but where we have never before been able to resolve the flaring region in the optical or X-rays. These observations will allow us to test synchrotron emission models for the X-ray outburst, constrain particle acceleration and loss timescales, and study the jet dynamics associated with this flaring component. Revisions 6 Oct 2004: Due to the demise of STIS we are replacing visits 1-7 with ACS/HRC observations in new visits 31-37. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10134 Cycle: 13 Title: The Evolution and Assembly of Galactic Disks: Integrated studies of mass, stars and gas in the Extended Groth Strip PI: Marc Davis This project is a 126-orbit imaging survey in F606W/F814W ACS to measure the evolution of galaxy disks from redshift z = 1.4 to the present. By combining HST imaging with existing observations in the Extended Groth Strip, we can for the first time simultaneously determine the mass in dark matter that underlies disks, the mass in stars within those disks, and the rate of formation of new stars from gas in the disks, for samples of >1, 000 objects. ACS observations are critical for this work, both for reliable identifications of disks and for determining their sizes and inclinations. Combining these data with the kinematics measured from high-resolution Keck DEIMOS spectra will give dynamical masses that include dark matter. Stellar masses can be measured separately using ground-based BRIK and Spitzer IRAC GTO data, while cross-calibrated star formation rates will come from DEEP2 spectra, GALEX, and Spitzer/MIPS. The field chosen is the only one where all multiwavelength data needed will be available in the near term. These data will show how the fundamental properties of disks {luminosity, rotation speed, scale length} and their scaling relations have evolved since z~1, and also will measure the build-up of stellar disks directly, providing fundamental tests of disk formation and evolution. In addition to the above study of disk galaxies, the data will also be used to measure the evolution of red-sequence galaxies and their associated stellar populations. ACS images will yield the number of red-sequence galaxies versus time, together with their total associated stellar mass. ACS images are crucial to classify red-sequence galaxies into normal E/S0s versus peculiar types and to measure radii, which will complete the suite of fundamental structural parameters needed to study evolution. We will measure the zeropoints of major scaling laws {Fundamental Plane, radius versus sigma}, as well as evolution in characteristic quantities such as L*, v*, and r*. Stellar population ages will be estimated from high-resolution Keck DEIMOS spectra and compared to SED evolution measured from GALEX, HST, Spitzer, and ground-based colors. Important for both disk and red-galaxy programs are parallel exposures to be taken with both NIC3 {J and H} and WFPC2 {B}. These are arranged so that ACS, WFPC2, and NIC3 all overlap where possible , providing a rich data set of galaxies imaged with all three HST cameras from B to H. These data will be used to measure restframe visible morphologies and UV star-formation rates for galaxies near the edge of the survey, to discover and count EROs below the Keck spectroscopic limit of R = 24, and to provide an improved database of photometric redshifts for galaxies in the overlap regions. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10135 Cycle: 13 Title: Unveiling the Progenitors and Physics of Cosmic Explosions PI: Shrinivas Kulkarni GRBs and XRFs are clearly highly asymmetric explosions and require a long-lived power source {central engine}. In contrast, nearby core-collapse events are essentially spherical explosions. However, the failure of spherical neutrino driven collapses has led to the idea that asymmetric energy release is essential for the explosion. The recent finding of a Type Ic SN in GRB 030329, the association of the low energy event GRB 980425 with SN 1998bw, the theoretical development discussed above and the rise of collapsar models make it timely to consider whether all these explosions contain engines. Given the uncertainties in theoretical modeling it is clear that observations are needed to guide models. A priori there is little reason to expect connection between the ultra-relativistic jet that powers the GRB and the explosive nucleosynthesis of the ~0.5 solar masses of Nickel-56 that powers the accompanying supernova. We propose a comprehensive program of ACS photometric searches {and measurements} for SNe associated with GRBs and XRFs. In concert, we will undertake ground-based spectroscopy to determine velocity widths, and measure engine parameters from pan-chromatic afterglow observations. Our goal is to produce a comprehensive database of engine and SN physical parameters against which theoretical modeling will be guided. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10136 Cycle: 13 Title: Post-AGB Stars in the Halo of M81 PI: Howard Bond Post-asymptotic-giant-branch {PAGB} stars of spectral types A-F are the brightest members of Population II. We have shown, using ground-based observations, that PAGB stars have tremendous potential as highly efficient standard candles and as tracers of halo populations and late stellar evolution. Our analysis of PAGB stars in archival HST images of M32, based on the equivalent of one orbit of HST time, precisely reproduces the accepted distance. We propose to obtain ACS/WFC and WFPC2 images of fields in the halo of M81, as another test of the PAGB method. We show that 4 orbits of HST data will produce a distance of comparable accuracy to the much more laborious Cepheid technique. If successful on M81, we will propose in the next cycle to measure the distance to Virgo using our method, a distance ladder that has only two rungs {trigonometric parallaxes of subdwarfs to calibrate PAGB stars in globular clusters, and then PAGB stars in Virgo}. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: GALAXIES ID: 10137 Cycle: 13 Title: Cluster Archeology: The Origin of Ultra-compact Dwarf Galaxies PI: Michael Drinkwater Ultra-compact dwarf {UCD} galaxies are a new type of galaxy we have discovered in the central regions of the Fornax and Virgo galaxy clusters. Our most recent observations in the Fornax Cluster show that UCDs outnumber normal galaxies in the centre of that cluster. Here we propose snapshot imaging of UCDs in the Fornax and Virgo clusters to test theories of how these fascinating objects formed. In particular we wish to image Virgo cluster UCDs for which we have ground-based Keck spectroscopy to test predictions that they formed more recently than the Fornax UCDs. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10138 Cycle: 13 Title: Searching for the Bottom of the Initial Mass Function PI: Kevin Luhman The minimum mass of the Initial Mass Function {IMF} should be a direct reflection of the physical processes that dominate in the formation of stars and brown dwarfs. To date, the IMF has been measured down to 10 M_Jup in a few young clusters; there is no sign of a low-mass cutoff in the data for these clusters. We propose to obtain deep images in the SDSS i and z filters {i=26, z=25} with the ACS/WFC on HST for a 800"x1000" field in the Chamaeleon I star-forming region {2 Myr, 160 pc}. By combining these HST data {0.8, 0.9 um} with comparably deep broad-band photometry from ground-based telescopes {1.2, 1.6, 2.2 um} and SIRTF {3.6, 4.5, 5.8, 8.0 um}, we will measure the mass function of brown dwarfs down to the mass of Jupiter and thus determine the lowest mass at which objects can form in isolation in a typical star forming cluster. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10139 Cycle: 13 Title: Structure of the Accretion Disk in the NLS1 NGC 4051 PI: Bradley Peterson We propose to obtain a UV spectrum of the narrow-line Seyfert 1 {NLS1} galaxy NGC 4051 on a target-of-opportunity basis when it goes into a faint state for the purpose of exploring the variable nature of the shape of the ionizing continuum in this source. Previous simultaneous X-ray and optical monitoring of this source reveals that at some times the X-rays and the He II 4686 emission line nearly disappear, while the UV/optical continuum and Balmer lines are weaker, but present and continue to vary. This suggests that there is a variable cutoff in the shape of the ionizing continuum, and in the faint state this occurs at low enough energies to affect all the strong UV lines. By comparing emission-line flux ratios in the low state to those in high states and with photoionization equibrium calculations, we can identify the cutoff energy. The cutoff energy may correspond to a transition radius in the accretion disk, inside of which the source has entered into a low-radiative efficiency mode. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10140 Cycle: 13 Title: Identification of a magnetic anomaly at Jupiter from satellite footprints PI: Denis Grodent Repeated imaging of Jupiter's aurora has shown that the northern main oval has a distorted 'kidney bean' shape in the general range of 90-140? System III longitude, which appears unchanged since 1994. While it is more difficult to observe the conjugate regions in the southern aurora, no corresponding distortion appears in the south. Recent improved accuracy in locating the satellite footprint auroral emissions has provided new information about the geometry of Jupiter's magnetic field in this and other areas. The study of the magnetic field provides us with insight into the state of matter and the dynamics deep down Jupiter. There is currently no other way to do this from orbit. The persistent pattern of the main oval implies a disturbance of the local magnetic field, and the increased latitudinal separation of the locus of satellite footprints from each other and from the main oval implies a locally weaker field strength. It is possible that these phenomena result from a magnetic anomaly in Jupiter's intrinsic magnetic field, as was proposed by A. Dessler in the 1970's. There is presently only limited evidence from the scarcity of auroral footprints observed in this longitude range. We propose to obtain HST UV images with specific observing geometries of Jupiter to determine the locations of the auroral footprints of Io, Europa, and Ganymede in cycle 13 to accurately determine the magnetic field geometry in the suggested anomaly region, and to either confirm or refute the suggestion of a local magnetic anomaly. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10141 Cycle: 13 Title: UV spectroscopy of the hot bare stellar core H1504+65 PI: Klaus Werner H1504+65 ist the hottest known white dwarf {Teff=200 000 K}. It has an extraordinary surface composition. The photosphere is devoid of hydrogen and helium. It is mainly composed of carbon and oxygen {by equal parts} and neon {2%}. We obviously see the exposed core of a former red giant. The evolutionary history of this unique object is unknown. We have identified magnesium absorption lines in the soft X-ray photospheric {Chandra} spectrum, which suggests that H1504+65 may be a O-Ne-Mg white dwarf. We will test this hypothesis by abundance determinations of Mg and Na. If confirmed, then H1504+65 would be the most compelling case for the existence of single O-Ne-Mg white dwarfs. ------------------------------------------------------------------------------ Prop. Type: GO Category: QUASAR ABSORPTION LINES/IGM ID: 10142 Cycle: 13 Title: The connection between star-forming galaxies and low-redshift quasar absorption line systems PI: Regina Schulte-Ladbeck We have positionally matched our database of over 19, 000 star-forming galaxies {SFGs} from the Sloan Digital Sky Survey {SDSS} against the SDSS QSO catalog. This has allowed us to discover nineteen bright QSOs with redshifts of less than or about one behind local SFGs. Two of the QSOs were fortuitously already observed with HST, and show strong Lyman alpha lines at the emission-line redshifts of the SFGs with which we matched them ------------------------------------------------------------------------------ Prop. Type: SNAP Category: COOL STARS ID: 10143 Cycle: 13 Title: Ultracool companions to the nearest L dwarfs PI: I. Reid We propose to conduct the most sensitive survey to date for low mass companions to nearby L dwarfs. We will use NICMOS to image targets drawn from a volume-complete sample of 70 L dwarfs within 20 parsecs. The combination of infrared imaging and proximity will allow us to search for T dwarf companions at separations as small as 1.6 AU. This is crucial, since no ultracool binaries are currently known with separations exceeding 15 AU. Only 10 dwarfs in this sample have previous HST observations primarily at optical wavelengths. With the increased sensitivity of our survey, we will provide the most stringent test to date of brown dwarf models which envisage formation as ejected stellar embryos. In addition, our observations will be capable of detecting binaries with mass ratios as low as 0.3, and will therefore also test the apparent preference for equal-mass ultracool binaries. Finally, our observations offer the best prospect to date of detecting companions significantly cooler than the coolest t dwarf currently known. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10144 Cycle: 13 Title: The Gas Environment of Comet 9P/Tempel 1 During the Deep Impact Encounter PI: Paul Feldman We propose a series of observations of the periodic comet 9P/Tempel 1 in conjunction with NASA's Deep Impact mission. This mission is a spacecraft that will release a 360 kg impactor into the nucleus of the comet on July 4, 2005. Our primary objective is to study the generation and evolution of the gaseous coma resulting from this impact. To this end we plan to obtain ultraviolet spectra with STIS before, during, and following the impact. As a secondary objective we will obtain wide-band images of the visual outburst resulting from the impact. We also plan to use the high resolution capability of the ACS/HRC, in conjunction with the camera on board the spacecraft, two weeks prior to impact, to determine the spatial orientation of active jets emanating from the comet's nucleus and to assess the potential hazards of these jets to the spacecraft. ------------------------------------------------------------------------------ Prop. Type: GO Category: STAR FORMATION ID: 10145 Cycle: 13 Title: Physical parameters of the upper atmosphere of the extrasolar planet HD209458b PI: Alfred Vidal-Madjar Every 3.5 days, the transits of the gaseous planet orbiting HD209458 offer the unique opportunity to investigate the spectral features of an extra-solar planetary atmosphere. Using HST, we first discovered the extended upper atmosphere of HD209458b through the detection of a 15% HI Lyman alpha absorption. We concluded that the hydrogen must be escaping the planet with a lower limit rate of 10^10 g/s {Vidal-Madjar et al. 2003}. Additional observations, subsequently allowed to detect OI and CII in the upper atmosphere implying that this atmosphere is hydrodynamically escaping {in "blow off", Vidal-Madjar et al. 2004}. Here we propose to further study this upper atmosphere to better constrain the "blow off" state by directly estimating the physical conditions and the flow characteristics. In particular we will determine the temperature and density at the base of the upper atmosphere {the thermosphere}, and the density distribution and ionization state just below that level. Comparison between the optical and ultraviolet occultation light curves will provide useful information on the molecular/haze content of the lower atmosphere. The observation of six HD209458b transits with HRC and SBC settings will allow the detection of many lines adressing these issues. The proposed observations will give us for the first time a detailed probe of the atmosphere of an "evaporating" extra-solar planet.With species as abundant as FeII or MgII, the damping wings in the strongest lines will start to form at levels around 1.9% absorption. Due to either the strength of the MgII doublet lines around 280 nm or the packing of FeII lines, strong absorptions arising from the accumulated damping wings should show up clearly in FeII and MgII. All these signatures should be easily detected even with the 40 to 100 Angstrom resolution of the PR200L prism in these spectral regions. In addition to these goals, any signature of molecules {e.g CO below 154 nm}, dust or haze should also show up as broad band absorption in both PR110L and PR200L settings. The estimate of the planet radius at different wavelengths in the UV would become possible for all efficient absorbers in this spectral range. The achievement of 0.1% precision in the occultation curves thus provides sensitivity high enough to potentially lead to important discoveries. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10146 Cycle: 13 Title: Solving the problem of the White Dwarf Cooling Sequence End in M4: an efficent approach PI: Luigi Bedin The end of the white dwarf {WD} cooling sequence {WDCS} has never been observed, despite the importance that it has in providing an age estimate of old stellar systems, independent from the standard method of the main sequence turn off. The best targets for this investigation are the closest stellar clusters, and, among them, globular clusters are the most interesting ones. Being the oldest stellar aggregates, they allow to probe the advanced WD cooling phases, and the independent age estimate coming from the end of their WDCS has an important cosmological impact. M4 is the best target for this investigation. Despite huge observational efforts, we still miss the end of its WDCS. The ACS camera offers a unique opportunity to identify it. Coupled with already existing observations, we here prove that we can finally reach it with only 10 HST orbits. This is probably the last opportunity we have for a large number of years. The data we are requesting here, will also be used to complete other two programs of great astrophysical impact: the observational detection of the main sequence hydrogen burning limit, and the measurement of the geometrical distance of M4. ------------------------------------------------------------------------------ Prop. Type: GO Category: COOL STARS ID: 10147 Cycle: 13 Title: Detecting the elusive low mass companion around epsilon Indi PI: Michael Endl We propose coronagraphic NICMOS observations of the nearby {d = 3.6 pc} K5V star epsilon Indi {HD 209100} to search for the unknown companion which causes a low amplitude radial velocity {RV} trend in our 11 years of precise Doppler measurements. This RV data set places a lower limit of 4.5 AU for the orbital semimajor axis of this companion. Moreover, the fact that the RV trend is lacking any sign of curvature over this long time period clearly points towards a much larger orbital separation. Epsilon Indi also has a T dwarf {binary} companion at a separation of 1400 AU. However, these brown dwarf companions are too distant from the primary to induce the observed RV variation. It is also unlikely that this nearby star has an unknown stellar {M dwarf} companion. The RV signal is thus most probably caused by a yet unknown giant planetary or brown dwarf companion at a separation of more than 5 AU. Because epsilon Indi is so near to the Sun, it constitutes an ideal target for high contrast imaging with NICMOS in its coronagraphic mode. Indeed, NICMOS coronagraphy is capable of detecting objects down to 15 Jupiter masses at separations greater than 2.3 arcseconds {S/N=25} - precisely the separation and mass range indicated by our Doppler spectroscopy. Only 2 orbits of HST/NICMOS observations could directly image the coolest and lowest mass companion ever found around a solar-type star. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10148 Cycle: 13 Title: The Masses of the Ultraluminous X-Ray Sources PI: Joel Bregman Ultraluminous X-ray sources are non-nuclear sources in normal disk galaxies that are second only to AGNs in point-source luminosity. These enigmatic objects are either stellar mass black holes that are super-Eddington emitters, or sub-Eddington emission from 1E3-1E4 Msolar black holes. We can distinguish between these models by a direct determination of the mass of the primary, which requires knowing the spectral type of the secondary, its period, and its orbital velocity around the black hole. We propose to obtain UV spectra to determine the spectral type of two ULX secondaries {optical counterparts}, to infer the masses and radii of the secondaries and their suitability for radial velocity studies. For another ULX secondary, we already obtained a UV spectrum showing it to be a B0I star, so we propose three additional observations, which will yield the characteristic orbital velocity, help constrain the period, and reveal if the primary is a 1E3-1E4 Msolar black hole, which would produce velocities > 1000 km/sec. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10149 Cycle: 13 Title: The Coevolution of Supermassive Black Holes and Galaxies at z~3 PI: Chien Peng The existence of strong correlations between the mass of supermassive black holes and galaxy bulge properties implies that there is an intimate connection between their formation and evolution. How do supermassive black holes grow and how did the correlations come about? Is the growth of supermassive black holes coeval with the growth of the bulge, and is a bulge necessary for AGN activity at high z? We propose to use HST NICMOS to image 9 low-luminosity broad-line AGNs at z~3 in the restframe B-band, identified through the Lyman-break technique. This sample is unique because the AGN luminosities are comparable to Seyfert-like nuclei at z~3, and thus are some of the lowest that have been selected optically. Because of the low total luminosity of the sample, the hosts are likely to be Lyman-break galaxies, which are believed to be the progenitor galaxies of the local Hubble sequence. The goal is to directly detect their host galaxies and to separate the AGN, in order to study the host galaxy morphology and luminosity. From measurement of the bulge luminosity and black hole mass {through available spectra}, we will study the black hole-bulge coevolution out to z~3. We will also compare the luminosity and morphology of these faint AGN hosts with the more luminous and massive host galaxies found in previous HST studies of quasars. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10150 Cycle: 13 Title: NICMOS observations of A1689 PI: Narciso Benitez The potential of galaxy clusters as ``cosmic telescopes'' has been known for a long time, but practical results in the pre-ACS era have been scarce due to two main problems: the uncertainty in determining the magnification distribution of the cluster {the ``optics'' of the instrument} and the presence of numerous bright cluster galaxies which cover the field of view and hinder the detection of background galaxies. We have developed techniques to solve these two problems working with our ACS observations of A1689, the most powerful lens in the sky, and for the first time we have been able to determine the "specifications" of a cosmic telescope with a useful level of precision, thanks to the detection and identification of more than 100 multiple images with reliable redshift information. We propose to observe the high magnification region in the A1689 field in the F110W band with a 3x3 mosaic of NIC3 pointings; the resulting image will reach a lens-corrected limiting magnitudes of 29.5 for point sources, surpassing in depth the UDF NICMOS observations and providing an unique dataset with multiple scientific returns. ------------------------------------------------------------------------------ Prop. Type: GO Category: QUASAR ABSORPTION LINES/IGM ID: 10151 Cycle: 13 Title: Testing the Warm-Hot Intergalactic Medium Paradigm PI: J. Howk Cosmological hydrodynamical simulations predict that ~30%-40% of the low-redshift baryons reside in a collisionally ionized phase {log T ~ 5 to 7} of the intergalactic medium {IGM} associated with large-scale, unvirialized filaments of galaxies. Recent surveys of O VI gas have lent some support to the presence of this warm-hot intergalactic medium {WHIM}, but the results are significantly limited by uncertainties in the ionization mechanism {photo- vs. collisionally ionized} and metallicity of the gas. We are pursuing a large program to test predictions of the WHIM and to improve existing measurements of the OVI absorbers. The primary goals are {i} to increase the redshift path for detection of the hottest IGM, previously only accessible through X-ray absorption studies, using EUV absorption from Ne VIII and Mg X, and {ii} to constrain the IGM physics using UV absorption from H I Ly-alpha, C III, C IV, and O VI. Our team has been awarded a FUSE Legacy program to probe the moderate-redshift WHIM using unique ionization diagnostics in the restframe EUV waveband, including O V, Ne VIII and Mg X. Here we propose to complement our FUSE Legacy program with STIS intermediate-resolution echelle-mode observations of five moderate-redshift {0.45 < z < 0.98} AGNs. The unique combination of FUSE EUV and STIS UV spectra will allow us {1} to test the current models of the WHIM by studying the ionization mechanisms responsible for producing highly-ionized metals in the IGM and determining the frequency of genuine high-temperature metal absorbers in the low-redshift IGM; {2} to investigate the relationship between WHIM and large-scale galaxy structures using galaxy redshift measurements obtained with DEIMOS on Keck and IMACS at Las Campanas Observatory; and {3} to determine the ionization state and metallicity of O VI absorbers in order to accurately assess their contribution to the total baryon budget. Finally, we will make high-level science products derived from these data freely available to the general astronomical community. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: COSMOLOGY ID: 10152 Cycle: 13 Title: A Snapshot Survey of a Complete Sample of X-ray Luminous Galaxy Clusters from Redshift 0.3 to 0.7 PI: Megan Donahue We propose a public, uniform imaging survey of a well-studied, complete, and homogeneous sample of X-ray clusters. The sample of 73 clusters spans the redshift range between 0.3-0.7. The samples spans almost 2 orders of magnitude of X-ray luminosity, where half of the sample has X-ray luminosities greater than 10^44 erg/s {0.5-2.0 keV}. These snapshots will be used to obtain a fair census of the the morphology of cluster galaxies in the cores of clusters, to detect radial and tangential arc candidates, to detect optical jet candidates, and to provide an approximate estimate of the shear signal of the clusters themselves, and potentially an assessment of the contribution of large scale structure to lensing shear. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10153 Cycle: 13 Title: Multi-wavelength Observations of Symbiotic Stars in Outburst PI: Charles Keyes To investigate the cause and nature of classical symbiotic outbursts, we initiated a program of multi-wavelength observations of these events. As evidence is mounting that collimated outflows {jets} may be associated with symbiotic outbursts, we also investigate conditions needed for jet production - a question with broad astrophysical relevance. The first target for our campaign - the 2000-2002 outburst of Z Andromedae - confirmed the utility and need for coordinated multi-wavelength observations to make progress in understanding the nature of the outburst mechanisms in symbiotic stars. FUSE data were the cornerstone of that project {which included data from the VLA, MERLIN, ground-based spectroscopy and photometry, Chandra, and XMM, but not HST}. Our Z And observations have motivated us to propose a new scenario that we term the "combination nova" which is triggered by a disk-instability. To test this new model, we received HST Cycle 12 and FUSE Cycle 4 time {through approximately 6/2004} to continue the multi-wavelength approach with observations at several epochs during the outburst of a second target-of-opportunity {TOO}. That TOO has not yet been triggered. We propose here to continue this TOO observing opportunity into Cycle 13 {to 7/2005}. FUSE Cycle 5 observations {to mid-2005} were recently approved. Coordinated XMM and VLA observations are also approved. The evolution of the UV spectrum throughout the outburst plays a vital role in distinguishing between the outburst models currently in contention for describing outburst behavior. Analysis of our first campaign has shown that HST observations can play a fundamental role in the multi-wavelength approach. The combination of high-resolution STIS and FUSE-band emission and absorption features, time-tagged observations, and continua provide a unique opportunity to probe the structure and ionization conditions in the outburst material that can not be accomplished with either ultraviolet region alone. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10154 Cycle: 13 Title: Morphology of z ~ 7-10 galaxies viewed through gravitational telescopes PI: Roser Pello The aim of these observations is to obtain deep z/ACS and H/NICMOS images in the core of two lensing clusters, A1835 and AC114, where a few z ~ 7-10 galaxy candidates have been selected from our ultra-deep JHK imaging program with Isaac/VLT. Spectroscopic observations have allowed to confirm 2 of these candidates thanks to the detection of faint emission lines identified as Lyman alpha at z=7.2 and 10. Our HST project is focused on two main goals: {1} the morphological confirmation of galaxy candidates lying near critical lines, and {2} the determination of the physical scales involved in star-forming regions at z ~ 7-10. These goals should have important implications on our present knowledge of the galaxy formation process in the early Universe. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10155 Cycle: 13 Title: A Mini-Survey of Interstellar Abundances in the Magellanic Clouds PI: Daniel Welty Studies of the interstellar medium in the Magellanic Clouds explore somewhat different environmental conditions from those typically probed in our own Galactic ISM. Apart from a few studies of individual sightlines, however, little is known about the abundances and depletions in the ISM of the LMC and SMC. HST spectra of three SMC stars indicate that Si and Mg {generally thought to be major dust constituents} are essentially undepleted in the SMC gas --- even for components with severe depletions of Fe and Ni. Similar "anomalous" Si depletions have now been seen in cycle 12 STIS spectra of one LMC star, though "normal" Si depletions are seen toward a second. Intriguingly, the "anomalous" Si depletions are all found for sightlines which probe regions where the 2175 A extinction bump is either absent {most of SMC} or very weak {LMC2}. We therefore propose a mini-survey of interstellar absorption lines toward 13 stars distributed throughout the LMC and SMC --- which would more than double the number of Magellanic Clouds sightlines with extensive and accurate interstellar abundance information. A single STIS E230M setting will include lines from Zn II, Si II, Fe II, Ti II, Cr II, Ni II, and several trace neutral species --- allowing the abundance/depletion pattern to be determined at many locations in the two galaxies. The analysis of these spectra will have significant implications for {1} making models of interstellar dust grains {which currently rely heavily on silicates}; {2} understanding the relationships between depletions, dust, and H_2 {which may be somewhat different in the Milky Way, LMC, and SMC}; and {3} interpreting the gas-phase abundances observed for more distant low-metallicity systems, such as the QSO absorption-line systems {which exhibit some similar properties}. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10156 Cycle: 13 Title: Saturn's Auroral Energy Deposition Coordinated with Cassini UVIS PI: John Clarke An in-depth study of Saturn's magnetosphere and auroral processes has begun in Jan. 2004 with coordinated HST STIS images of Saturn's aurora while the approaching Cassini measures the solar wind. This program is expected to establish the degree of solar wind control of Saturn's aurora. The beginning of the Cassini orbiter tour of the Saturn system in July 2004 will offer new opportunities for collaborative science. The energetics of Saturn's auroral processes can best be studied via low resolution UV spectra of the emissions and the auroral "color ratio". The geometry of the initial Cassini orbits provides the best observing geometry for UVIS measurements of auroral energetics when it is close to Saturn on the night side. At such times, it will be possible to have simultaneous observations of Saturn's southern / dayside aurora with HST STIS and the northern / nightside aurora with Cassini UVIS. Both the distributions of the auroral emissions and the energy of the precipitating particles can be measured simultaneously at conjugate points north and south. This proposal is to conduct one such simultaneous observation, which will demonstrate the potential for future cycles. We request 5 HST orbits to observe a large fraction of one complete Saturn rotation at the same time as Cassini UVIS. The rotational coverage has been shown to be of central importance in recent STIS images of Saturn's auroral activity, which is concentrated in an "active sector" connected with the strongest SKR radio emissions. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10157 Cycle: 13 Title: Bulges or disks in the centers of late-type spirals? PI: C. Carollo In a simple view of the Hubble sequence, smaller bulges should be rescaled versions of bigger bulges. Bulges however have been found to change their structural properties with decreasing luminosity, approaching at the faintest end a disk-like, exponential light profile. This indicates a complex mass-dependent bulge formation history. Particularly, the intermediate-to-small size bulges have been suggested to form due to secular evolution processes within their host disks. However, the alleged small bulges may even be 'simply' denser inner regions of the disks. Two major ingredients are missing in order to {a} understand the nature of bulges in the disk-dominated galaxies, {b} establish whether and which secular evolution processes actually occur, and {c} in which mass range they are preferentially active: {1} High-resolution numerical simulations of disk secular evolution, to provide a quantitative basis for interpreting real data; {2} Observational diagnostics which can break the degeneracy between very cold, dense disks and relatively hot bulges, and to compare with the simulations. We are carrying out a large N-body + SPH simulations campaign to settle the first issue. Stellar kinematics are the ideal observational diagnostics. We have acquired ground kinematic data for the medium-sized bulges. However, both the spectroscopic and the spatial resolution requirements necessary to trace the relative contributions of cold and hot motions become very stringent at the faint-end of the bulge sequence: only the HST can provide radially-extended kinematics for the smallest bulges. We therefore ask for STIS/G750M spectroscopy to measure internal resolved stellar kinematics for two small bulges selected from our previous HST imaging program. Even just these two "data-points" in this unexplored mass-regime will allow significant progress in the understanding of the origin of the Hubble sequence: Complemented by our ground-study of the medium-sized bulges, they will allow us to establish whether the ratio of cold-to-hot motions in bulges in the intermediate-to-small mass regime depends on the bulge mass, and, by comparing with our simulations, to constrain the initial conditions and physical parameters that allow disk secular evolution processes to grow central bulges similar to those that are observed along the entire Hubble sequence. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10158 Cycle: 13 Title: ACS Observations of the Gravitational Lens B1608+656: Characterizing the Einstein Ring PI: Christopher Fassnacht We request time to obtain ACS deep images of the B1608+656 gravitational lens system to fully characterize its enclosing Einstein ring with high signal-to-noise ratio {SNR}. These data will allow us to determine the gravitational potential of the lens, locally, to several percent accuracy and, combined with the three independent time delays, measure H_0 to much better than 10% precision. For this goal, we have developed powerful new lens modeling codes that make use of the full brightness distribution of the Einstein ring in lens systems. The B1608+656 system is ideal for our new code. It has precisely measured time delays, a well-determined stellar velocity dispersion, and an Einstein ring that is not dominated by the lensed nuclear emission of the background source. When combined with high-SNR images of Einstein rings, the new modeling codes provide qualitatively different and much improved analysis of the ring emission than was previously possible. The proposed ACS observations will reach the SNR at which the new modeling code can be fully exploited {SNR=5 per pixel}. Our simulations show that these new data will allow us to reduce the total uncertainties in H_0 derived from the system by at least a factor of two, to the 5-7% level for this system. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10159 Cycle: 13 Title: Characterizing the Sources Responsible for Cosmic Reionization PI: Richard Ellis Our group has demonstrated the role that massive clusters of galaxies, acting as powerful cosmic lenses, can play in locating sources with modest mass and star formation rate beyond redshifts z~5-6 likely to be representative of those responsible for cosmic reionization. The large magnifications, possible in the critical regions of well-constrained clusters, bring sources into view that would lie at or beyond the limits of conventional exposures such as the UDF. Recently, using deep ACS and NICMOS imaging, we have located a low mass source at z=7.05 whose UV continuum slope is apparently steeper than for normal star-forming galaxies. We propose a deep ACS grism exposure to confirm the nature of this source and further ACS and NICMOS imaging of well-studied clusters to locate further examples. The grism spectroscopy will conclusively determine the UV SED of this source and our 3-color survey will constrain the redshift, star-formation rate, and SED of additional 66.5, with more than 2.5 Msun/yr of star formation {our survey limit}. Before the advent of the next generation of observational facilities, our search technique may represent the only way to reliably select and characterize the likely population of galaxies during the epoch of reionization. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10160 Cycle: 13 Title: The nuclear scattering geometry of Seyfert galaxies PI: Andrew Robinson Orientation-based unification schemes are now well-established as the basis for understanding the relationships between different classes of AGN. However, our recent study of the optical polarization properties of Seyfert 1 galaxies indicates that scattered light emerging from these objects often follows a different path to that in Seyfert 2's, indicating that the simplest unification geometry is incomplete. We have developed a generic scattering model for Seyfert nuclei which includes a compact, equatorial scattering region located within the circum-nuclear torus and the 'classic' polar scattering region outside it. We propose to test this model by using NICMOS to make NIR imaging observations that will allow us to isolate the two scattering regions within individual objects. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10161 Cycle: 13 Title: Fresh ammonia-ice on Jupiter: The northern equatorial region. PI: Imke de Pater The proposed multi-band imaging of one of the most dynamic regions on Jupiter will complement recent space-based infrared datasets and will provide crucial constraints to models of Jovian atmospheric dynamics. NICMOS is sensitive to the jovian troposphere at and above the visible cloud decks. We selected six NICMOS filters with varying levels of atmospheric opacity to observe cloud features as they rotate from the central meridian to the limb, a strategy that will maximize the vertical resolution of our retrievals of cloud heights, haze opacity, and gaseous ammonia concentration. With these filters and the excellent NICMOS spatial resolution {nearly an order of magnitude improvement over Galileo NIMS images of the northern equatorial region}, we will determine the smaller-scale structure of fresh NH3 clouds and provide cloud heights as constraints for models of convection and dynamics associated with 5-micron hotspots. HST is essential for this project, since no other observatory can provide the necessary spatial resolution, and no ground-based or space-based telescopes can observe the ammonia bands we have selected. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10162 Cycle: 13 Title: Resolving the Thermal Conduction Front in the Bubble S308 PI: You-Hua Chu Heat conduction is one of the most fundamental processes in the interstellar and intergalactic media. Many astronomical systems contain cool {<10^4 K} gas in contact with hot {10^6 -10^8 K} gas; at the contact surfaces, heat conduction occurs and may play an essential role in the thermal structure and evolution of the system. Observations of thermal conduction fronts have been extremely limited. Conventionally observations use absorption lines of collisionally ionized high ions as tracers of 1-3x10^5 K gas in the conduction front. Such observations allow the determination of column densities but not the relative locations of these tracer ions. Emission-line observations of a clear-cut, edge-on conduction front are needed to study the physical structure of a thermal conduction front. We have identified a clean-cut, edge-on conduction front in the circumstellar bubble S308, using XMM-Newton X-ray observations and ground-based optical images and spectra. We request HST STIS spectroscopic observations of the NV and CVI emission lines in the transition region from the hot interior gas to the cool nebular shell. These observations, combined with our complementary observations at optical, FUV, and X-ray wavelength, allow us to determine the spatially-resolved temperature profile of a thermal conduction front. Comparisons with models further allow us to assess the efficiency of thermal conduction. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10163 Cycle: 13 Title: Weighing the Most Luminous Main-Sequence Star in the Galaxy PI: Anthony Moffat NGC 3603 is the most massive, visible giant HII region in our Galaxy and virtually a clone of R136, the famous supercluster in the core of the 30 Dor region in the LMC. NGC 3603 harbors three young, extremely luminous, hot stars which mimic the spectral appearance of WN6ha stars. As tailored atmosphere analysis reveals, these stars are unevolved, very massive stars on the main sequence. In fact, these stars have the potential of being the most massive main sequence stars known in our Galaxy. One of these WN6ha stars is a double-eclipsing binary with a 3.7724d period. We propose here to use HST/STIS to carry out, for the first time, repeated, high-quality spectroscopy of this binary in order to derive Keplerian orbits for both components and thus directly measure their masses. Additional photometry will considerably refine the solution for the inclination angle. Whether or not the mass of the WN6ha {and possibly also its companion} star significantly exceeds 60 M_sol, the current directly-observed, upper limit of main sequence stars, will allow us to put models for massive stars to the test. As a by-product of our observations, we will also monitor the two remaining WN6ha stars in NGC 3603. At least one of them shows strong indications for binarity. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10164 Cycle: 13 Title: HD 62542: Probing the Bare, Dense Core of an Interstellar Cloud PI: Daniel Welty The line of sight to HD 62542 is remarkable for its unusual UV extinction, high column densities of various molecules, and apparent dearth of diffuse atomic gas. The main interstellar cloud appears to be a small, dense {n_H ~ 500--1000 cm^-3}, molecular knot whose more diffuse outer layers have been stripped away by stellar winds and shocks. As such, it provides an ideal venue for investigating the properties of dense, molecular gas --- with minimal confusion from any associated diffuse gas. We propose to obtain high resolution, moderately high S/N STIS spectra of C I, CO and its isotopomers, C_2, C II, O I, and many other atomic species. Those data will be used to compare various diagnostics of the physical conditions {e.g., C I and O I fine structure excitation, CO and C_2 rotational excitation}, to determine the relative abundances of the various CO isotopomers {fractionation}, and to determine the depletions of various elements in dense gas {the predicted severe depletions have likely been masked by associated diffuse gas in other cases}. Understanding the fractionation and excitation of CO in this relatively simple case will aid in understanding its behavior in other more complex regions {important because CO and its isotopomers are often used to trace and characterize molecular gas when H_2 cannot be measured}. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10165 Cycle: 13 Title: Determination of orbits and colors for two new binaries in the Koronis asteroid family PI: William Merline We propose to measure color and orbital properties of two asteroid binaries in the Koronis family discovered in our SNAP-9747 survey. The best previously studied asteroid binary system, Ida/Dactyl, is also in the Koronis family. Differential space weathering measured on the Ida and Dactyl surfaces has been a powerful constraint on models of satellite formation mechanisms and satellite survivability. HST offers the unique opportunity for similar measurements of these much smaller, main-belt binaries. The new satellites are believed to have formed through different collisional mechanisms than Ida/Dactyl. Further, with a set of 4 relative position measurements for each of the two systems, added to the discovery snapshots, we will determine and compare the densities of the primaries with Ida {a large, 31.5 km, asteroid with density 2.6+-0.5 g/cm^3, measured by the Galileo flyby}. In contrast, {17246} and {22899} are 4.5 km bodies that are likely to have been restructured since the family-forming event by subsequent collisions. As all are members of the same family, differences in density would constrain bulk composition and internal structure {e.g. shard vs. rubble-pile}. Hence, these measurements are likely to further elucidate the mechanisms for formation of satellites. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10166 Cycle: 13 Title: ACS and WFPC2 Stellar Photometry in the Kepler Mission Target Field PI: William Borucki We will observe three regions at the Galactic Equator {GE} to determine the number of stars in the magnitude range from 18 to 25 in the target field of the NASA Kepler mission. This mission will search for Earth-size planets orbiting other stars. The field is a twelve by twelve degree square in Cygnus. It abuts the GE. The detection technique is to search photometrically for planetary transits. Faint eclipsing binaries that are not spatially resolved from the target star by Kepler may cause confusion, leading to false positive detections. The HST is uniquely capable of determining the potential magnitude of the issue in the region of the GE, where stellar densities are extremely high. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10167 Cycle: 13 Title: Imaging of Ices in Circumstellar Disks PI: Alycia Weinberger The link between the material of the interstellar medium and the ultimate composition of planets lies in the way gas and dust are processed in circumstellar disks. Planet formation models rely upon a knowledge of the disk constituents and temperature profiles to simulate how small grains eventually combine into terrestrial planets and gas giant cores. Disks around other stars may be analogs for our own early Solar System and thus allow the direct measurement of such phenomena. Only recently, however, have well-resolved images of dust disks around several late T Tauri or main sequence stars been secured. HST provides a uniquely stable platform for making such sensitive high dynamic range images. Now, for those handful of disks already resolved, we are able to go beyond the discovery phase and begin making astrophysical measurements to deepen our understanding of the course of disk evolution. We therefore propose a multi-wavelength study with NICMOS designed to discover the spatial distribution of two common Solar System materials -- methane and water ices -- in other systems. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10168 Cycle: 13 Title: Spatially Resolved Spectroscopy of HR 4796A's Dust Ring PI: Alycia Weinberger HST's high-contrast capabilities provide exciting imaging of circumstellar debris disks with complex structures. In particular, broad-band imaging using the coronagraphs in NICMOS and STIS has elucidated the disk morphology of HR 4796A exquisitely, but can only provide colors, not detailed compositional information on its dust. With spectra, we will measure the detailed albedo of the disk dust over a large wavelength range and search for interstellar medium-like molecules and water ice. We will also use our spatially resolved spectra for very high angular resolution profiles of the disk width to constrain models for planets circling inside the dust. We have demonstrated in a previous program how to use STIS for spatially resolved disk spectroscopy. We now propose to use our technique to study HR 4796A. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10169 Cycle: 13 Title: Star Formation in Luminous Infrared Galaxies: giant HII Regions and Super Star Clusters PI: Almudena Alonso-Herrero Luminous Infrared Galaxies {LIRGs, LIR = 10^11-10^12Lsol} and Ultraluminous Infrared Galaxies {LIR>10^12Lsol} account for approximately 75% of all the galaxies detected in the mid-infrared in the redshift range z=0-1.5. In the local universe it is found that LIRGs are predominantly powered by intense star formation {SF}. However, the physical conditions and processes governing such dramatic activity over scales of tens to a few hundred parsecs are poorly known. In the last decade HST has been playing a significant role, mainly with the discovery of super star cluters {SSCs}, and more recently, giant HII regions. Based on observations of a few LIRGs, we found that these giant HII regions and associated SSCs appear to be more common in LIRGs than in normal galaxies, and may dominate the star formation activity in LIRGs. A larger sample is required to address fundamental questions. We propose an HST/NICMOS targeted campaign of a volume limited sample {v<5200km/s} of 24 LIRGs. This proposal will probe the role of giant HII regions in the overall energetics of the current star formation, their relation to SSCs, and the dependence of star formation properties on other parameters of LIRGs. Such detailed knowledge of the SF properties of LIRGs in the local universe is essential for understanding galaxies at high redshift. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: SOLAR SYSTEM ID: 10170 Cycle: 13 Title: Atmospheric Variability on Uranus and Neptune PI: Kathy Rages We propose Snapshot observations of Uranus and Neptune to monitor changes in their atmospheres on time scales of weeks, months, and years. Uranus is rapidly approaching equinox in 2007, with another 4 degrees of latitude becoming visible every year. Recent HST observations during this epoch {including 6818: Hammel, Lockwood, and Rages; 7885: Hammel, Karkoschka, and Marley; 8680: Hammel, Rages, Lockwood, and Marley; and 8634: Rages, Hammel, Lockwood, Marley, and McKay} have revealed strongly wavelength-dependent latitudinal structure and the presence of numerous visible-wavelength cloud features in the northern hemisphere. Long-term ground-based observations {Lockwood and Thompson 1999} show seasonal brightness changes whose origins are not well understood. Recent near-IR images of Neptune obtained using adaptive optics on the Keck Telesccope together with images from our Cycle 9 Snapshot program {8634} show a general increase in activity at south temperate latitudes as well as the possible development of another Great Dark Spot. Further Snapshot observations of these two dynamic planets will elucidate the nature of long-term changes in their zonal atmospheric bands and clarify the processes of formation, evolution, and dissipation of discrete albedo features. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10171 Cycle: 13 Title: Ultraviolet Spectrum of the Binary Millisecond Pulsar J0437-4715 PI: George Pavlov PSR J0437-4715 is the nearest and the brightest millisecond {recycled} pulsar, and the only one detected at near-optical wavelengths. We detected it with the HST STIS/FUV-MAMA detector and found that its FUV spectrum is consistent with being emitted from the neutron star surface with a temperature of about 0.1 MK, surprisingly high for such an old object. We also found evidence of an emission line at 1372 A, tentatively interpreted as a Zeeman component of the hydrogen Ly-alpha line in a magnetic field of 700 MG. Unfortunately, the spectrum was imaged in a region of strong detector background, which strongly hampered the spectral and timing analyses. We propose to re-observe the pulsar with the FUV-MAMA, placing the target in a low-background region, and also observe it with the NUV-MAMA to obtain the spectrum and pulsations in a broad UV range. The spectral analysis will allow us to measure the temperature of the full neutron star surface and test the origin of the heating of old neutron stars. Confirmation of the spectral line would lead to a first direct measuremnt of the magnetic field and radius of a spin-powered neutron star and uniquely constrain the equation of state of superdense matter. The NUV spectrum and pulsations will also probe the magnetospheric emission and the thermal structure of the cool white dwarf companion. ------------------------------------------------------------------------------ Prop. Type: GO Category: STAR FORMATION ID: 10172 Cycle: 13 Title: Our Galaxy's most promising Super Star Cluster candidate, Westerlund 1: Tip of the Iceberg? PI: Richard de Grijs Recent ground-based observations have revealed that the highly reddened Galactic cluster Westerlund 1 is the current best and by far the nearest "Young Massive Star Cluster" {YSC} candidate, i.e. a young {< 10 Myr}, dense and massive {> 10, 000 Mo} object of which until recently 30 Doradus in the LMC was believed to be the nearest example. However, extrapolations of the locally derived cluster luminosity function indicate that perhaps up to a hundred similar objects should exist within the Galaxy. The close-up view of a YSC provided by Westerlund 1 allows us to obtain an unprecedented glimpse of the process of massive cluster formation, evolution and fate, which are among the very key issues in modern astrophysics. Utilising deep ACS and NICMOS imaging and sophisticated N-body and Monte Carlo simulations, we will address key questions regarding Westerlund 1's nature, formation and dynamical evolution. These include, What are the initial conditions with which Westerlund 1 was born? To what degree was mass segregation really primordial? Has the binary fraction changed during the short cluster lifetime? Do we expect the cluster to have a population of stellar-mass black holes? Does the cluster harbour an intermediate-mass black hole in its core? Is Westerlund 1 unique as a Galactic YSC? How similar is the cluster to the massive "Arches" and "Quintuplet" Galactic Centre clusters, and to 30 Doradus? With an expected life-span of > 100 Myr, it is conceivable that there should be more YSCs like Westerlund 1 in the Galactic disk. Our dynamical simulations will help us determine the ultimate fate of such clusters, allowing us to at least begin to answer the question of Westerlund 1's uniqueness in the context of the Galaxy's stellar populations. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: AGN/QUASARS ID: 10173 Cycle: 13 Title: Infrared Snapshots of 3CR Radio Galaxies PI: William Sparks Radio galaxies are an important class of extragalactic objects: they are one of the most energetic astrophysical phenomena and they provide an exceptional probe of the evolving Universe, lying typically in high density regions but well-represented across a wide redshift range. In earlier Cycles we carried out extensive HST observations of the 3CR sources in order to acquire a complete and quantitative inventory of the structure, contents and evolution of these important objects. Amongst the results, we discovered new optical jets, dust lanes, face-on disks with optical jets, and revealed point-like nuclei whose properties support FR-I/BL Lac unified schemes. Here, we propose to obtain NICMOS infrared images of 3CR sources with z<0.3 as a major enhancement to an already superb dataset. We aim to deshroud dusty galaxies, study the underlying host galaxy free from the distorting effects of dust, locate hidden regions of star formation and establish the physical characteristics of the dust itself. We will measure frequency and spectral energy distributions of point-like nuclei, expected to be stronger and more prevelant in the IR, seek spectral turnovers in known synchrotron jets and find new jets. We will strongly test unified AGN schemes and merge these data with existing X-ray to radio observations. The resulting database will be an incredibly valuable resource to the astronomical community for years to come. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: GALAXIES ID: 10174 Cycle: 13 Title: Dark-matter halos and evolution of high-z early-type galaxies PI: Leon Koopmans Gravitational lensing and stellar dynamics provide two complementary methods to determine the mass distribution and evolution of luminous and dark-matter in early-type {E/S0} galaxies. The combined study of stellar dynamics and gravitational lensing allows one to break degeneracies inherent to each method separately, providing a clean probe of the internal structure of massive galaxies. Since most lens galaxies are at redshifts z=0.1-1.0, they also provide the required look-back time to study their structural and stellar-population evolution. We recently analyzed 5 E/S0 lens galaxies between z=0.5 and 1.0, combining exquisite Hubble Space Telescope imaging data with kinematic data from ground-based Keck spectroscopy, placing the first precise constraints on the dark-matter mass fraction and its inner slope beyond the local Universe. To expand the sample to ~30 systems -- required to study potential trends and evolution in the E/S0 mass profiles -- we propose to target the 49 E/S0 lens-galaxy candidates discovered by Bolton et al. {2004} from the Sloan Digital Sky Survey {SDSS}. With the average lens rate being 40% and some systems having a lensing probability close to unity, we expect to discover ~20 strong gravitational lenses from the sample. This will triple the current sample of 9 E/S0 systems, with data in hand. With the sample of 30 systems, we will be able to determine the average slope of the dark-matter and total mass profile of E/S0 galaxies to 10% and 4% accuracy, respectively. If present, we can simultaneously detect 10% evolution in the total mass slope with 95% confidence. This will provide unprecedented constraints on E/S0 galaxies beyond the local Universe and allow a stringent test of their formation scenarios and the standard cosmological model. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: HOT STARS ID: 10175 Cycle: 13 Title: STIS Snapshot Survey of Boron Abundances in Early-B Stars PI: Charles Proffitt Boron abundances in massive stars provide a unique constraint for new theoretical models of stellar evolution that include rotation. We propose to use STIS to measure the B III doublet near 2066 Angstroms in a large sample of early-B stars. A high priority will be placed on obtaining abundances for several stars in each of a number of different young clusters, assocations, and star forming regions. This will allow quantitative comparision with theoretical predictions of rotationally driven mixing in early B stars as function of mass, age, and rotation rate. Since boron abundance measurements are not possible for large vsin{i} values, and sin{i} is not known for individual stars, a large sample is required to statistically test the predictions of boron depletion as a function of the true rotation rate. For bright nearby stars {25 targets} we will use the G230MB grating and obtain very high S/N {>200:1}. This avoids the need for an ND filter which would discard 99% of the photons. Spectral synthesis techniques will allow us to derive accurate abundances despite the moderate resolution of this grating, even for stars with relatively high vsin{i} values. This is especially important in testing rotational models, as current abundance measurements are mostly for stars with much lower than average rotation rates. For fainter, more distant stars {27 targets} we will use the E230M or E230H grating with the 0.2x0.2 aperture. ------------------------------------------------------------------------------ Prop. Type: GO Category: STAR FORMATION ID: 10176 Cycle: 13 Title: Coronagraphic Survey for Giant Planets Around Nearby Young Stars PI: Inseok Song A systematic imaging search for extra-solar Jovian planets is now possible thanks to recent progress in identifying "young stars near Earth". For most of the proposed young {<~ 30 Myrs} and nearby {<~ 60 pc} targets, we can detect a few Jupiter-mass planets as close as a few tens of AUs from the primary stars. This represents the first time that potential analogs of our solar system - that is planetary systems with giant planets having semi-major axes comparable to those of the four giant planets of the Solar System - come within the grasp of existing instrumentation. Our proposed targets have not been observed for planets with the Hubble Space Telescope previously. Considering the very successful earlier NICMOS observations of low mass brown dwarfs and planetary disks among members of the TW Hydrae Association, a fair fraction of our targets should also turn out to posses low mass brown dwarfs, giant planets, or dusty planetary disks because our targets are similar to {or even better than} the TW Hydrae stars in terms of youth and proximity to Earth. Due to the recent cancellation of SM4, HST will inevitably degrade into a 2-gyro mode soon and high contrast survey programs like our own cannot be carried out with two gyros. This means that the HST cycle 13 may be the last chance to find young Solar System analogs in the coming decade. Should HST time be awarded and planetary mass candidates be found, proper motion follow-up of candidate planets will be done with ground-based AOs. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10177 Cycle: 13 Title: Solar Systems In Formation: A NICMOS Coronagraphic Survey of Protoplanetary and Debris Disks PI: Glenn Schneider Until recently, despite decades of concerted effort applied to understanding the formation processes that gave birth to our solar system, the detailed morphology of circumstellar material that must eventually form planets has been virtually impossible to discern. The advent of high contrast, coronagraphic imaging as implemented with the instruments aboard HST has dramatically enhanced our understanding of natal planetary system formation. Even so, only a handful of evolved disks {~ 1 Myr and older} have been imaged and spatially resolved in light scattered from their constituent grains. To elucidate the physical processes and properties in potentially planet-forming circumstellar disks, and to understand the nature and evolution of their grains, a larger spatially resolved and photometrically reliable sample of such systems must be observed. Thus, we propose a highly sensitive circumstellar disk imaging survey of a well-defined and carefully selected sample of YSOs {1-10 Myr T Tau and HAeBe stars} and {> app 10 Myr} main sequence stars, to probe the posited epoch of planetary system formation, and to provide this critically needed imagery. Our resolved images will shed light on the spatial distributions of the dust in these thermally emissive disks. In combination with their long wavelength SEDs the physical properties of the grains will be discerned, or constrained by our photometrically accurate surface brightness sensitivity limits for faint disks which elude detection. Our sample builds on the success of the exploratory GTO 7233 program, using two-roll per orbit PSF-subtracted NICMOS coronagraphy to provide the highest detection sensitivity to the smallest disks around bright stars which can be imaged with HST. Our sample will discriminate between proposed evolutionary scenarios while providing a legacy of cataloged morphologies for interpreting mid- and far-IR SEDs that the recently launched Spitzer Space Telescope will deliver. This project cannot be done from the ground, and becomes untenable for HST after Cycle 13 under the anticipated use of two-gyro pointing control mode. ------------------------------------------------------------------------------ Prop. Type: GO Category: STAR FORMATION ID: 10178 Cycle: 13 Title: Imaging Polarimetry of Young Stellar Objects with ACS and NICMOS: A study in dust grain evolution PI: Dean Hines The formation of planetary systems is intimately linked to the dust population in circumstellar disks, thus understanding dust grain evolution is essential to advancing our understanding of how planets form. By combining {1} the high resolution polarimetric capabilities of ACS and NICMOS, {2} powerful 3-D radiative transfer codes, and {3} observations of objects known to span the earliest stellar evolutionary phases, we will gain crucial insight into the initial phases of dust grain growth: evolution away from an ISM distribution. Fractional polarization is a strong function of wavelength, therefore by comparing polarimetric images in the optical and infrared, we can sensitively constrain not only the geometry and optical depth of the scattering medium, but also the grain size distribution. By observing objects representative of the earliest evolutionary sequence of YSOs, we will be able to investigate how the dust population evolves in size and distribution during the crucial transition from a disk+envelope system to a disk+star system. The proposed study will help to establish the fundamental time scales for the initial depletion of ISM-like grains: the first step in understanding the transformation from small submicron sized dust grains, to large millimeter sized grains, and untimely to planetary bodies. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10179 Cycle: 13 Title: A Coordinated NICMOS and XMM Experiment to Observe the Variability of Sgr A* PI: Farhad Yusef-Zadeh The massive black hole Sgr A* at the Galactic center has recently shown not only quiescent emission at near-IR wavelengths, but also flare activity with quasi-periodicity of 17 minutes. Our research group has been granted two blocks of observing time with XMM-Newton to monitor the spectral and temporal properties of Sgr A*. Simultaneously with these X-ray observations, we will also monitor Sgr A* at radio, submillimeter, near-IR, and gamma-ray wavelengths. We propose to use NICMOS in parallel with the XMM observations to provide evidence of a well-defined minimum periodicity in the spectrum of flare periodicities. This, combined with periodicity in the near-IR line emission, would strengthen the claim that the emitting gas resides at the innermost stable circular orbit around the GC black hole, thus measuring the spin parameter of a massive black hole. Current groundbased near-IR data suggest a spin parameter of ~0.5. In addition, the correlation pattern of emission over a wide spectrum would elucidate a key issue of how to explain the low luminosity of Sgr A*. The NICMOS on HST is the only instrument that can accurately measure the 17 minute quasi-periodic variability of Sgr A* because of the long time baseline over which HST can observe Sgr A* in parallel with XMM-Newton. ------------------------------------------------------------------------------ Prop. Type: GTO/OS Category: ID: 1018 Cycle: 0 Title: IMAGING AND SPECTROSCOPY OF A COMPLETE SAMPLE OF BRIGHT NEARBY QUASARS: II. SPECTROSCOPY (CYCLE 0) PI: John Bahcall FOS spectra will be obtained for seven optically bright PG quasars [3C 273, PG 0953+415, PG 1116+215, PKS 1302-102, PG 1700+518, GQ Com, and 3C 249.1] with Mb 1.25, providing conclusive evidence of an earlier epoch of cosmic deceleration. The full sample of 16 new SNe Ia match the cosmic concordance model and are inconsistent with a simple model of evolution or dust as alternatives to dark energy. Understanding dark energy may be the biggest current challenge to cosmology and particle physics. To understand the nature of dark energy, we seek to measure its two most fundamental properties: its evolution {i.e., dw/dz}, and its recent equation of state {i.e., w{z=0}}. SNe Ia at z>1, beyond the reach of the ground but squarely within the reach of HST with ACS, are crucial to break the degeneracy in the measurements of these two basic aspects of dark energy. The SNe Ia we have discovered and measured with HST in Cycle 11, now double the precision of our knowledge of both properties. Here we propose to quadruple the sample of SNe Ia at z>1 in the next two cycles, complementing on-going surveys from the ground at z<1, and again doubling the precision of dark energy constraints. Should the current best fit model prove to be the correct one, the precision expected from the current proposal will suffice to rule out a cosmological constant at the 99% confidence level. Whatever the result, these objects will provide the basis with which to extend our empirical knowledge of this newly discovered and dominant component of the Universe, and will remain one of the most significant legacies of HST. In addition, our survey and follow-up data will greatly enhance the value of the archival data within the target Treasury fields for galaxy studies. ------------------------------------------------------------------------------ Prop. Type: GTO/OS Category: ID: 1019 Cycle: 0 Title: THE STELLAR DENSITY DISTRIBUTIONS IN THE CENTERS OF GALACTIC GLOBULAR CLUSTERS PI: John Bahcall Short exposures will be made of all galactic globular clusters with distance moduli less than 15.5 mag and galactic latitude above or below 15 degrees. A search will be made for cusps in the stellar density distributions and the colors will be measured for the brightest stars in the cores of the clusters. ST observations are required in order to reach the innermost regions of the clusters with sufficient resolution to separate individual stars. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10190 Cycle: 13 Title: The Star Formation History and Metallicity Evolution of M33: A Comprehensive Study of Disk Evolution PI: Donald Garnett We will obtain deep, panchromatic imaging photometry of stellar populations in four fields ranging from 0.5 to 4 scale lengths across the disk of the Local Group spiral M33. The observations are designed to detect the oldest main-sequence turnoffs in three outer disk fields, and to reach the crowding limit in the innermost field. We will combine the photometry data with information we already have in-hand on abundances from stars and H II regions in M33 to derive the star formation history and metallicity evolution of the M33 disk. The information from our four fields will allow us to obtain {1} the ages of the oldest disk stars and the radial variation of their ages; {2} the radial variation of the star formation history and its nature {e.g., constant, declining, or bursting}; and {3} the metallicity distribution in each field and the time evolution of the metallicity gradient. Our team, an experienced mix of photometrists, spectroscopists, and galaxy evolution theorists, will use the results from this program to construct a comprehensive chemo-dynamical model for the M33 disk. This detailed study of M33 will be a key in developing an understanding of the formation and evolution of disks that can be applied to studies of disks at both low and high redshift, and will also yield a wealth of information on stellar populations, chemical evolution, and star clusters that will be of great value to future investigators. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10191 Cycle: 13 Title: A Fundamental Test of Accretion Physics with NGC 4203 PI: Joseph Shields The rapid evolution of quasars indicates that supermassive black holes in galaxy nuclei spend most of their time in a relatively quiescent state. Studies of nearby galaxies demonstrate that many such black holes are accreting at a low rate, and appear as low-luminosity active galactic nuclei {LLAGNs}. Theoretical arguments suggest that the mode of accretion onto a central black hole may be very different in LLAGNs as compared to high-luminosity systems. The LINER NGC 4203 provides an excellent opportunity to investigate quantitatively the accretion process in a LLAGN, and hence the typical accretion state for a supermassive black hole. Cycle 7 STIS data acquired at one position angle reveal double-peaked H-alpha emission in the nucleus that may trace an accretion disk, and spatially resolved emission that places an upper limit on black-hole mass. We propose observations with STIS to map the two-dimensional velocity field of the circumnuclear gas disk in the central regions of NGC 4203, in order to measure the black-hole mass. This parameter is essential for testing theoretical models of accretion, determining the mass accretion rate, and estimating the radiative efficiency for accreted matter. The results will be important for making sense of LLAGNs, and for translating their measured luminosity into accretion rates that trace the growth of black holes. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10192 Cycle: 13 Title: Jupiter's Upper Stratospheric Hazes Probed with Ganymede PI: Erich Karkoschka I propose to observe a disappearance of Ganymede behind the dark limb of Jupiter with five filters of the ACS/HRC camera. Two exposures in each filter can be taken during such an event. The images will provide the spectral variation of the altitude of the apparent limb of Jupiter. The altitude of the apparent limb is dependent on the presence of hazes in Jupiter's stratosphere. Hazes of vertical optical depths below 0.001 could be detected with these observations, providing an extremely sensitive probe of high hazes. The observations probe altitudes levels near the 1-mb pressure level, for which we have very limited data. The creation of aerosols, their growth, and their transport by winds is currently a mostly theoretical study. It would significantly benefit from constraints derived from the proposed observations. ACS/HRC is the only instrument capable of the required spatial resolution in the ultraviolet. Furthermore, a favorable geometry of Ganymede's orbit occurs only once every six years. This proposal achieves unique results with a minimum of HST time. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10193 Cycle: 13 Title: Can Narrow-Line Regions in Luminous AGN be Enormously Large? PI: Hagai Netzer We propose to obtain long-slit optical spectra of three nearby quasars with the largest reported narrow-line regions {NLRs}. These sources have been shown to be the cornerstone of a most interesting size--luminosity relationship in AGN-NLRs which, we suspect, is very problematic. A two-orbit HST/STIS observation, per source, will allow us to measure several narrow emission lines from H_beta through H_alpha and [S II] at several distances along the spatial direction. We will thus be able to classify the line excitation mechanism, estimate the gas density as a function of distance from the center, and more properly define the 'NLR size'. This will allow us to test the idea that the NLR conditions in these quasars are very different from those observed in low luminosity AGN and, specifically, that some of the narrow emission lines have a star forming origin. Together with our IR spectra of high-redshift quasars, we will be able to test the newly discovered NLR size-luminosity relationship in AGN and the AGN-starburst connection at the high luminosity end. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: HOT STARS ID: 10194 Cycle: 13 Title: Towards a global understanding of accretion physics - Clues from an UV spectroscopic survey of Cataclysmic Variables PI: Boris Gaensicke Accretion inflows and outflows are fundamental phenomena in a wide variety of astrophysical environments, such as Young Stellar Objects, galactic binaries, and AGN. Observationally, cataclysmic variables {CVs}, interacting white dwarf/main sequence binaries, are particularly well suited for the study of accretion processes. Furthermore, CVs that are born with a donor more massive than the white dwarf are potential progenitors of supernovae type Ia. We are currently carrying out a STIS UV spectroscopic snapshot survey of CVs to fully exploit the diagnostic potential of these objects for our understanding of accretion physics. We analyze the STIS spectra with state-of-the-art accretion disc model spectra {SYNSPEC}, testing our current knowledge of accretion disk structure, and thereby, providing new insight into the currently poorly understood process of viscous dissipation. In addition, we use our parameterised wind model PYTHON for the analysis of the radiation driven accretion disc wind spectra, assessing the fundamental question whether the mass loss rate correlates with the disc luminosity. Our survey data also identify a number of systems in which the white dwarf significantly contributes to the UV flux, permitting an analysis of the impact of mass accretion on the evolution of these compact stars. Finally, anomalous N/C emission line flux ratios unmistakably identify CVs that started out with a donor more massive than the white dwarf but failed to reach the Chandrasekhar limit. Determining the number of these "failed SNIa" will provide crucial input for the population models of this type of system, and, consequently, improve the predictions on the number of white dwarf binaries that actually do overcome the Chandrasekhar limit. While the data obtained so far are of excellent quality, the number of targets that have been observed so far is too small for a statistically significant analysis. We propose here to extend this survey into Cycle 13, building a homogenous database of accretion disc and wind outflow spectra covering a wide range of mass transfer rates and binary inclinations, and sampling the N/C abundances of at least 100 CVs. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10195 Cycle: 13 Title: Probing the Surroundings of a Highly Luminous Redshift 6.5 Galaxy PI: James Rhoads We propose deep images of a recently discovered galaxy at z=6.535, which is among the most luminous Lyman-alpha emitting galaxies known at high redshift. The brightness and rarity of this source imply that it is associated with a high peak in the matter density distribution. {It is the brightest Lyman alpha source in 2e5 comoving Mpc3, with a luminosity of 6 L*.} Further objects in this peak are expected to be visible with HST's sensitivity. The Lyman alpha line has a large rest frame equivalent width, with a lower bound >100 Angstroms. Such a large equivalent width would be impossible for objects embedded in neutral gas, and instead requires either that {a} the universe was reionized before z=6.5 or {b} the galaxy resides in a local ionized bubble, in which case an additional contribution to the ionizing photon budget from presently undetected neighbors is required. With 19 orbits of ACS and NICMOS imaging, we will measure this object's morphology and spectral energy distribution, thus searching for either active nuclei or old stellar populations. We will also search for possible neighbors, which could establish the first known galaxy group at z>6, and may provide sufficient ionizing flux to allow the escape of the observed Lyman alpha photons in a neutral universe. If neighbors are not found, it will lead to an upper bound on the neutral fraction in the general IGM at z=6.5. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10196 Cycle: 13 Title: Morphologies of a new class of rest-frame optical selected high redshift galaxies PI: Marijn Franx We have obtained deep very Js, H, Ks imaging with the VLT of two fields with excellent optical imaging, in order to study high redshift galaxies. Using these Near-IR images, we identified a class of galaxies with Js - Ks color larger than 2.3. Photometric redshifts and spectroscopic follow-up showed that their mean redshift is 2.5 +- 0.7. These galaxies are complementary to Lyman break selected galaxies: the overlap is minimal, and the rest-frame optical colors of the Js-Ks selected galaxies are much redder. Their contribution to the stellar mass density is comparable to that of Lyman breaks in our fields. SED fits and Near-IR spectroscopy of the Js-Ks selected galaxies indicate median ages between 1 and 2 Gyr, a factor of 3-5 older than the ages of Lyman break galaxies estimated by similar methods. They are likely the oldest galaxies at z=2.5, and may be evolving into the most massive galaxies at z=0. We propose to obtain images of the spectroscopically confirmed Js-Ks galaxies with the NICMOS/NIC3 camera in the H band. These galaxies lie the field of MS1054-03, for which we have excellent groundbased and HST optical imaging. The increased depth and spatial resolution of the NICMOS imaging will allow us to determine the restframe optical morphologies of the Js - Ks galaxies, in order to study their intensity profiles and regularity, to decompose the largest galaxies in bulges and disks, to measure scale lengths, and to look for evidence of merging and recent star formation. This study would provide us unique insight into the nature of these red galaxies, their evolutionary history and their likely descendants at low redshift. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10197 Cycle: 13 Title: The Astrophysical Parameters of Very Metal-Poor Halo Binaries PI: Elliott Horch Little is currently known concerning the mass-luminosity relation {MLR} of Population II stars. In Cycle 10, we began an initial study with FGS1 to resolve a sample of known spectroscopic binaries preselected as high-velocity and/or low metallicity objects. This has resulted in significant new information about the astrophysical parameters of metal-poor stars, but was limited mainly to intermediate metallicities, not to true Population II stars. A new sample of metal-poor spectroscopic binaries identified by Latham and his collaborators {e.g. Latham et al 2002} contains three new very metal-poor objects resolvable with FGS. We propose to observe these binaries and obtain additional observations of two very important resolved targets from our initial sample. As with that program, we will couple the already-known spectroscopic orbits with astrometric information which only FGS can deliver at present. To ensure that the most will be gained from these data, we als o request observations of three metal-poor single stars to be used as calibration objects. In combination with results from our previous program, these observations can be expected to resolve the question of the location of the Population II main sequence and give valuable insight into the accuracy of isochrone fitting for determination of globular clusters ages. Due to the combination of target magnitudes and expected separations, no object in this sample can be resolved without the unique capabilities of FGS. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: STELLAR POPULATIONS ID: 10198 Cycle: 13 Title: Probing the Dynamics of the Galactic Bar through the Kinematics of Microlensed Stars PI: Przemyslaw Wozniak The observed optical depths to microlensing of stars in the Galactic bulge are difficult to reconcile with our present understanding of Galactic dynamics. The main source of uncertainty in those comparisons is now shifting from microlensing measurements to the dynamical models of the Galactic bar. We propose to constrain the Galactic bar models with proper motion observations of Bulge stars that underwent microlensing by determining both the kinematic identity of the microlensed sources and the importance of streaming motions. The lensed stars are typically farther than randomly selected stars. Therefore, our proper motion determinations for 36 targeted MACHO events will provide valuable constraints on the dynamics of bulge stars as a function of distance. The first epoch data for our proposed events is already available in the HST archive so the project can be completed within a single HST cycle. The exceptional spatial resolution of HST is essential for completion of the project. Constraints on the total mass in the bulge will ultimately lead to the determination of the amount of dark matter in inner Galaxy. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: GALAXIES ID: 10199 Cycle: 13 Title: The Most Massive Galaxies in the Universe: Double Trouble? PI: Mariangela Bernardi We are proposing an HST snapshot survey of 70 objects with velocity dispersion larger than 350 km/s, selected from the Sloan Digital Sky Survey. Potentially this sample contains the most massive galaxies in the Universe. Some of these objects may be superpositions; HST imaging is the key to determining if they are single and massive or if they are two objects in projection. The objects which HST imaging shows to be single objects are interesting because they potentially harbor the most massive black holes, and because their existence places strong constraints on galaxy formation models. When combined with ground based data already in hand, the objects which HST imaging shows are superpositions provide valuable information about interaction rates of early-type galaxies as well as their dust content. They also constrain the allowed parameter space for models of binary gravitational lenses {such models are currently invoked to explain discrepancies in the distribution of lensed image flux ratios and separations}. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10200 Cycle: 13 Title: Dark Matter Constraints from the Merging Cluster 1E0657-56 PI: Christine Forman-Jones We propose five orbits of ACS Wide Field Camera observations {three orbits with F814W, one with F606W, and one with F435W} to investigate the unique, high velocity merging cluster 1E0657-56{z=0.296}. Coupling the ACS images with deep Chandra observations and ground-based imaging will allow us to compare maps of the intracluster medium, the dark matter, and the galaxies from which we can directly estimate the self-interaction cross-section of dark matter, the dominant mass component in clusters and the Universe. These observations, combined with hydrodynamic simulations, will either rule out the range of cross-sections proposed to alleviate problems with collisionless dark matter or unambiguously detect and measure the self-interaction cross-section. A secondary objective is to quantify the impact of a supersonic merger on star formation and the morphological evolution of cluster galaxies. The geometry of 1E0657-56 {with the merger nearly in the plane of the sky} coupled with the subcluster velocity {4500 km/s} accurately constrains the timescale of the merger. In particular since the subcluster traversed the dense core of the main cluster only 0.15 Gyr ago, star formation induced by the core passage will be clearly visible. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10201 Cycle: 13 Title: The Origin of Dwarf Galaxies and Steep Luminosity Functions in Clusters PI: Christopher Conselice Clusters of galaxies contain an overdensity of dwarfs compared to the field. The origin of these dwarfs is unknown, but a large fraction of them did not form through standard collapses early in the universe. Some dwarf ellipticals in clusters have metal rich and young stellar populations while others contain old metal poor populations, suggesting multiple formation mechanisms and time scales. We propose to test the idea that dwarfs descend from galaxies accreted into clusters during the past 8 Gyrs by correlating ages and metallicities of dwarfs with their internal structures - spiral arms, bars, and disks. If dwarfs originate from more massive galaxies then these features should be common in metal rich and young dwarfs. On the other hand, if no correlation is found it would suggest that dwarfs form through in-situ collapses of gas in the intragalactic medium after the universe was reionized. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: HOT STARS ID: 10202 Cycle: 13 Title: Resolving OB Binaries in the Carina Nebula, Resuming the Survey PI: Edmund Nelan In March 2002 we carried out a small, high-angular resolution survey of some of the brightest OB stars in the Carina Nebula with FGS1r in an attempt to resolve binary systems which had thus far evaded detection by other techniques. Of 23 stars observed, 5 new OB binaries were discovered with component separations ranging from 0.015" to0.325". This yield over the spatial domain of FGS1r's angular resolution, coupled with published statistics of the incidence of OB stars in short-period spectroscopic, and long-period visual binaries suggests that the fraction of binarity or multiplicity among OB stars is near unity. Our unexpected resolution of the prototype O2 If* star HD 93129A as a 55 milli-arcsecond double is a case in point that great care must be excerised when one attemps to establish the IMF and upper-mass cuttoff at the high-mass end of the HR diagram. We propose to resume the survey to observe a larger, statistically meaningful sample of OB stars to establish a firm assessment of multiplicity at the high-mass end of the IMF in these clusters. We will also investigate the single-star/binary-star status of several astrophysically important, individual stars in order to enable a better understanding of the evolution of high-mass stars. ------------------------------------------------------------------------------ Prop. Type: AR Category: COOL STARS ID: 10203 Cycle: 13 Title: The Deep Lamp Project PI: Thomas Ayres Space Telescope Imaging Spectrograph is the most sophisticated space-borne spectrometer ever built, probably the last of its kind for some time to come. A key virtue of STIS is that its medium- and high-resolution echelle modes provide access to broad intervals of the vacuum ultraviolet spectrum in a single shot. Another virtue is the validation of the wavelength scales by periodic observations of an onboard hollow-cathode emission line source. Tying together the different echelle orders by means of the accurately known lamp spectrum enables a wide range of studies that exploit differential comparisons of velocity diagnostics in stellar, interstellar, and even extragalactic spectra. Despite the importance of the wavelength calibrations, however, they are done only infrequently {once a year}. While STIS undoubtedly must be one of the most stable orbiting spectrographs ever designed, possible thermal distortions of the instrument might cause small nonlinear deviations of the wavelength scales and thereby impact the velocity precision. The existing wavecal data sets are separated too far apart in time to isolate short-term thermal fluctuations from long-term secular behavior, and the routine WAVELINEs taken with every grating switch are too underexposed to reveal any differential behavior across the spectrum, aside from a simple zero-point offset. I therefore propose to obtain a series of deep lamp exposures in a few representative modes of the NUV and FUV MAMAs to search for and characterize short-term differential distortions of the echelle formats. This work also will provide an important dataset to test new approaches to derive the basic dispersion relations, such as the effort underway by the Physical Modeling Group at ESA's ST-ECF. The calibration campaign can be scheduled in pure parallel mode with no loss of orbits from the Cycle 13 science program. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10204 Cycle: 13 Title: Evolution of Light Echoes of SN 1993J PI: Ben Sugerman SN 1993J is the nearest SN in the last decade, and only one of seven objects to produce confirmed light echoes. Our analyses of archival HST/WFPC2 datareve aled that the SN has illuminated at least two light-echo structures in the galaxy M81. Those echoes appear to define two sheets of dust, located roughly 260 ly and 770 ly in front of the SN, which are the first, and most efficient, 3-D probes of the ISM in M81. The echoes not only reveal the ISM's structure, but also constrain the density, composition and grain-size of its dust. Echoes are transient events, and as they change on timescales shorter than a year, continued monitoring will reveal new illuminated material, tracing interstellar and circumstellar structure. We propose a modest and highly efficient campaign by HST to image these and yet undiscovered echoes toward SN 1993J. Such observations will build the first direct 3-D map of the ISM within a million cubic parsecs of M81's spiral arm, and may glimpse the circumstellar environment affected by the projenitor's mass loss. Such results probe the nature of extragalactic dust, reveal spatio-kinematic information about the M81's disk, tightly constrain its internal extinction, and under the proper circumstances, provide an independent distance measurement to the host galaxy. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10205 Cycle: 13 Title: Critical STIS Spectroscopy and ACS Imagery at the Top of the IMF PI: Nolan Walborn We shall observe two key massive hot stars to investigate the effects of multiplicity and rotational mixing on their parameters and evolution. {1} The prototype O2 If* star HD 93129A dominates the compact cluster Trumpler 14, one of the ionizing clusters of the Carina Nebula. It has been an anchor point for analyses of the most massive stars. Unexpectedly, it has been resolved as a 55 mas binary by FGS. The derived delta m of 0.9 implies that the companion may be similar to the O3 dwarfs HD 93128 and HD 93129B {3" from A} in Tr 14. Recent radio and X-ray data suggest that the HD 93129A system is a colliding-wind binary. We propose to resolve the system spectroscopically with STIS in both the optical and FUV. Also, we plan an orbit of very short ACS exposures on this key cluster to obtain resolved multicolor photometry of its crowded inner members for the first time. {2} The recent discovery of a CNO dichotomy among five O2 giants in the Magellanic Clouds provides a new evolutionary diagnostic for the most massive stars, which is related to their initial rotational velocities. The abundance anomalies are seen in the UV wind spectra as well as optical lines. We propose to observe the FUV spectrum of the LMC ON2 star LH10-3061 with STIS to support further analysis, since it is the only one of these stars lacking UV data. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10206 Cycle: 13 Title: What drives the outflows in powerful radio galaxies? PI: Clive Tadhunter There is increasing speculation that activity-induced outflows are an important feedback mechanism in evolution of galaxy bulges, yet uncertainties remain about the nature, dominant driving mechanism and powers of the outflows. In order to address these issues, we propose to make deep ACS and STIS observations of two compact radio sources in which we recently found unequivocal evidence for powerful emission line outflows, and in which all the potential drivers for the outflows -- quasar nuclei, relativistic jets and starbursts -- are known to be present. Using the unique capabilities of HST/ACS we will map the outflow regions in these sources at high spatial resolution and thereby determine the dominant outflow driving mechanism. In addition, by combining the morphological information from the ACS data with information on the kinematics and physical conditions derived from STIS and ground-based spectra, we will determine the mass outflow rates and powers in the outflows. This will be the first comprehensive study of the near-nuclear outflows in radio galaxies. Such studies are crucial for determining whether the activity associated with powerful extragalactic radio sources has a major impact on the evolution of the host early-type galaxies. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10207 Cycle: 13 Title: Star Formation in Damped Lya Galaxies: Testing the Connection with the Lyman Break Population PI: Jason Prochaska The principal challenge of damped Lya {DLA} research is to identify and study the stellar components of these galaxies. Although two decades of absorption-line research has yielded the HI gas content, metallicity, velocity fields, molecular and dust content of these galaxies only a handful have been studied in emission. Therefore, it has been very difficult to compare the DLA galaxies with the successful surveys of high z galaxies discovered in emission {e.g. Lyman break galaxies; LBG}. This is particulary important given that DLA systems are the probable precursors to galaxies like the Milky Way. Because the DLA systems are identified toward bright background quasars, deep observations at high spatial resolution with astable PSF are essential and only HST provides the observing capability. Recently, two major advances have greatly enhanced the prospects for measuring emission from DLA host galaxies: {1} we have developed a new spectroscopic technique for inferring the star formation rates {SFR} of the DLA which enables one to pre-select the brightest candidates; {2} the high spatial resolution and sensitivity of the ACS represents a major improvement over previous capabilities. We will obtain deep V-band images with the ACS of 5 high z DLA with the highest inferred apparent optical magnitudes. The complete survey will offer a robust satistical analysis of: {a} the extent and morphology of the DLA star forming regions; {b} the likelihood that the DLA and LBG correspond to the same population of protogalaxies; {c} a test of the protogalactic clump models favored by CDM cosmology. We emphasize this program will offer a major advance over all previous studies. Finally, we will complement these HST observations with an extensive observing campaign {IFU spectroscopy and deep IR imaging} on the Keck, VLT, and Magellan telescopes to provide the most extensive dataset yet on the physical properties of high z DLA. ------------------------------------------------------------------------------ Prop. Type: GO Category: COOL STARS ID: 10208 Cycle: 13 Title: NICMOS Differential Imaging Search for Planetary Mass Companions to Nearby Young Brown Dwarfs PI: Wolfgang Brandner We propose to use the differential spectral imaging capability of HST/NICMOS {NIC1} to search for planetary mass companions. We target the twelve most nearby {within 30 pc}, isolated {no known close companion}, and young {< 1Gyr} brown dwarfs. All of them have spectral type L and show signs of Lithium absorption, which clearly proves their substellar nature and youth. Planetary mass companions with masses down to 6 Jupiter masses, and at separations larger than 3 A.U. are bright enough for a direct detection with HST/NICMOS using the spectral differential imaging technique in two narrow-band filters placed on and off molecular bands. The proposed project has the potential to lead to the first direct detection of a planetary mass object in orbit around a nearby brown dwarf. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10209 Cycle: 13 Title: On the evolutionary status of extremely hot helium stars - are the O{He} stars successors of the RCrB stars? PI: Thomas Rauch We propose UV spectroscopy of the four unique post-AGB stars of spectral type O{He} in order to understand the origin of their peculiar surface abundances. These stars are the only known amongst the hottest post-AGB stars {effective temperatures > 100, 000 K} whose atmospheres are composed of almost pure helium. This chemistry markedly differs from that of the hydrogen-deficient post-AGB evolutionary sequence with objects which have carbon dominated atmospheres {PG1159 stars and Wolf-Rayet central stars}. While PG1159 and Wolf-Rayet stars are the result of a late helium-shell flash, this scenario cannot explain the O{He} stars. Instead, they are possibly double-degenerate mergers. We speculate that the four O{He} stars represent evolved RCrB stars, which also have helium dominated atmospheres. We aim to determine the C, N, O, and Si abundances precisely, in order to proof this evolutionary link. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10210 Cycle: 13 Title: Groups of Dwarf Galaxies: Pools of Mostly Dark Matter? PI: R. Tully Within 5 Mpc, there are 6 groups with well-known luminous galaxies but there also appears to be a comparable number of groups containing only dwarfs. If these dwarf entities are truly bound then M/L values are an order of magnitude higher than values found for groups with luminous spiral galaxies. There are theoretical reasons to anticipate that low mass halos may frequently be mostly dark. The dynamical influence of low mass halos is negligible in familiar groups with luminous members. By contrast, a study of the dynamics of `groups of dwarfs' may provide direct evidence of the existence of dark matter potential wells with few baryons. The goal of the present study is to gather detailed information on the 3-D distribution of dwarf galaxies suspected to lie within 7 groups of dwarfs within 5 Mpc. Distances with 7% relative accuracy can be measured with the Tip of the Giant Branch method with ACS and integrations within 1 orbit per target. ------------------------------------------------------------------------------ Prop. Type: GO Category: QUASAR ABSORPTION LINES/IGM ID: 10211 Cycle: 13 Title: A Combined HST/Chandra Study for Finding the Baryons in the Low Redshift Universe. PI: Smita Mathur The main reservoir of low redshift baryons is still ``missing'': All the observed stellar and gaseous components add up to a factor of ten below the abundance predicted by big bang nucleosynthesis. Hydrodynamic cosmological simulations predict that a large fraction of the low redshift baryons should reside in a warm/hot diffuse intergalactic medium {IGM}, detectable via an ``X-ray forest'' of high excitation metal lines, but blind searches of X-ray lines are extraordinarily difficult with present technology. A first hint of this warm-hot IGM may have been found in recent studies of OVI absorption towards background quasars. However, the significance of OVI absorbers to the total baryon budget is uncertain and UV observations alone cannot determine the physical conditions in the IGM. We propose STIS/E140M observations to search for intervening OVI absorbers towards two quasars that are bright enough in X-rays for follow-up Chandra spectroscopy. The combined UV/X-ray study provides a powerful tool to {1} assess the cosmological significance of OVI absorbers; {2} determine their physical properties using OVII/OVI and OVIII/OVI ratios; and {3} pursue detection and study of the warm-hot IGM. ------------------------------------------------------------------------------ Prop. Type: GO Category: COOL STARS ID: 10212 Cycle: 13 Title: A Critical Test for Radiatively Driven Hot Winds in Cool Stars PI: Alex Lobel We propose STIS observations of the C IV resonance emission line profiles for the two brightest short-period classical Cepheid variables Delta Cep and Beta Dor, to critically test if P Cygni-type profiles form in the hot transition region plasmas of their pulsating upper atmospheres. Recent FUSE observations of the cool {non-variable} G-supergiant Alpha Aqr {and Beta Aqr} show a distinct P Cygni-type profile in warm transition region emission lines of C III. The observations reveal supersonic wind outflow velocities that exceed ~140 km/s, based on our semi-empiric radiative transfer models. The models demonstrate that optically thick supersonic winds occur in the outer atmospheres of cool giant and supergiant stars, at kinetic gas temperatures well above 80 kK. STIS observations of cool regular pulsating Cepheid variables will confirm or reject our present hypothesis that these peculiar P Cygni-type line shapes form in a supersonic accelerating wind structure that is {partly} driven by a radiative atmospheric acceleration mechanism, generally adopted for driving the much faster winds of hot luminous stars. STIS observations of the detailed line shapes of hot transition region emission lines in Cepheids can establish an important physical link between the radiation-driven wind theory of hot stars, and the acoustic/magnetic wave-driven wind theory of cool stars. The proposed high-resolution far-UV spectra of these important pulsating cool stars will be an invaluable contribution to the HST Archive. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10213 Cycle: 13 Title: Optical identification of two nearby Isolated Neutron Stars through proper motion measuremnt. PI: Silvia Zane Aim of this proposal is to perform high-resolution imaging of the proposed optical counterparts of the two, radio silent, isolated neutron stars RXJ1308.6+2127 and RX J1605.3+3249 with the STIS/50CCD. Imaging both fields with the same instrumental configuration used in mid 2001 by Kaplan et al {2002; 2003}, will allow us to measure the objects' position and to determine their proper motions over a time base of nearly four years. The measurement of proper motions at the level of at least few tens mas/yr, expected for relatively nearby neutron stars, would unambigouosly secure the proposed optical identifications, not achievable otherwise. In addition, the knowledge of the proper motion will provide useful indications on the space velocity and distance of these neutrons stars, as well as on the radius. Constraining these parameters is of paramount importance to discriminate between the variety of emission mechanisms invoked to explain their observed thermal X-ray spectra and to probe the neutron star equation of state {EOS}. The determination of the proper motion is a decisive step toward a dedicated follow-up program aimed at measuring the objects' optical parallax, thus providing much firmer constrains on the star properties, again to be performed with the STIS/50CCD. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10214 Cycle: 13 Title: ACS/HRC imaging of two very bright ultra-luminous X-ray sources {ULXs} PI: Roberto Soria We propose broad- and narrow-band ACS/HRC imaging of two very bright ultraluminous X-ray sources {ULXs} in NGC 4559. Our main objectives are: to identify the optical counterparts; to determine their masses and evolutionary stages; to determine the nature of mass transfer in the ULX systems; to determine the properties of the stellar population in the ULX fields {eg, metal abundance, age}. With these observations, integrated with our Chandra, XMM-Newton, HST/WFPC2 and CHFT data, we will test the models for the nature and mechanisms of formation of the accreting black holes in ULXs. Moreover, one of the two ULXs is in a peculiar star-forming complex: we have suggested that it is an expanding wave of star-formation triggered by a dwarf galaxy plunging through the outer disk of NGC 4559. The ACS observation will also allow us to test this hypothesis. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10215 Cycle: 13 Title: STIS follow-up spectroscopy of Seyfert galaxies from Cycle 11 near-UV imaging survey PI: Thaisa Storchi-Bergmann We propose a near-UV {3000-5500AA} long-slit spectroscopic study of a sample of 23 Seyfert galaxies with bright circumnuclear U-band structures, selected from our Cycle 11 ACS near-UV snapshot survey. This survey collected HST U-band images for 78 galaxies, which also have optical and near-IR images available in the archive. We propose to enrich this image database with STIS spectra in the near-UV. The novel aspect of the present proposal is the availability of the near-UV images which will allow us to select the best slit centering and orientation to probe the circumnuclear structures. Our goal is to investigate the nature of these structures, characterizing the circumnuclear continuum and ionizing source of these galaxies at a spatial resolution of $sim$10 parsecs, where we will probe the black hole environment. With the proposed observations, we will derive properties of the circumnuclear stellar populations of the selected galaxies {ages, masses and metallicities}, evolutionary effects connecting the growth of the black hole with the growth of the galaxy bulge, as well as the relation between the black hole mass, accretion rate {luminosity} and the circumnuclear stellar population properties. This dataset will also allow us to study the effect of the bulge and black hole on the evaporation of young star clusters in these galaxies. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10216 Cycle: 13 Title: Co-evolution of spheroids and black holes PI: Tommaso Treu The masses of the giant black holes in galaxies are correlated with the luminosities, masses, and velocity dispersions of their host spheroids. This empirical connection of phenomena on widely different scales {from sub-parsec to kiloparsec} suggests that the evolution of a galaxy and its central black hole are closely linked. We propose to test various unified formation models, by measuring the cosmic evolution of the black hole/spheroid relations, back to z=0.37 {a lookback time of 4 Gyrs}. We will obtain 1-orbit ACS images of a sample of 20 Seyfert 1 galaxies, for which we already have extensive new ground-based measures of the black hole masses and the stellar velocity dispersions. HST resolution is required for accurate measurement of the nonstellar AGN continuum, and the luminosity and effective radius of the bulge of each host galaxy. This will complete the set of observables needed to map the co-evolution of spheroids and black-holes. The proposed sample is the minimum required to make the first measure of the black hole mass/bulge correlation and of the fundamental plane for active galaxies outside the local Universe. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10217 Cycle: 13 Title: The ACS Fornax Cluster Survey PI: Andres Jordan The two rich clusters nearest to the Milky Way, and the only large collections of early-type galaxies within ~ 25 Mpc, are the Virgo and Fornax Clusters. We propose to exploit the exceptional imaging capabilities of the ACS/WFC to carry out the most comprehensive imaging survey to date of early-type galaxies in Fornax: the ACS Fornax Cluster Survey. Deep ACS/WFC images -- in the F475W {g'} and F850LP {z'} bands -- will be acquired for 44 E, S0, dE, dE, N and dS0 cluster members. In Cycle 11, we initiated a similar program targeting early-type galaxies in the Virgo Cluster {the ACS Virgo Cluster Survey; GO-9401}. Our proposed survey of Fornax would yield an extraordinary dataset which would complement that already in hand for Virgo, and allow a definitive study of the role played by environment in the structure, formation and evolution of early-type galaxies and their globular cluster systems, nuclei, stellar populations, dust content, nuclear morphologies and merger histories. It would also be a community resource for years to come and, together with the ACS Virgo Cluster Survey, constitute one of the lasting legacies of HST. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10218 Cycle: 13 Title: Unveiling the nature of the 321s orbital period binary RXJ0806.3+1527 PI: GianLuca Israel This porposal is aimed at studying one of the potentially most important binary system in our Galaxy, namely RXJ0806.3+1527. Our group discovered a 321s periodic modulation in its optical and X-ray flux and we poposed that it originates form the orbital motion {the shortest known} of a white dwarf around another lighter white dwarf. VLT optical spectra showed faint and broad {1500km/s FWHM} HeII {mainly} emission lines, even though the presence of H can not be completely ruled out due to spectral resolution. Moreover, recent XMM observations with the OM confirmed that the broad band energy spectrum of this source peaks in the UV band, making it one of the best target for HST studies. Here we propose to use the STIS spectroscopic capability of HST in the TIME-TAG mode. The latter mode is extremely well suited for our purposes, since will allow us, among other things, to perform, for the first time, an Orbital Phase Spectroscopy of the expected He lines {also those of C, N and O are expected} in the STIS spectra. We expect to finally probe the nature of the source by following the emission line centroid shift as a function of the orbital phase, making RXJ0806.3+1527 a single-component spectroscopic binary and opening a new perspective in the field of double degenerate systems {the emission lines of the greatest part of which are dominated by the effect of the disk rotation}. ------------------------------------------------------------------------------ Prop. Type: GO Category: STAR FORMATION ID: 10219 Cycle: 13 Title: Are Dust Disks and Circumstellar Gas Around Young A Stars Unrelated Phenomena? PI: James Neff Young stars with circumstellar material are common, but their properties vary greatly. Current studies strongly suggest that Beta Pictoris {A5 V} is an early solar system. If the high-density, high-velocity circumstellar gas falling toward Beta Pic were fueled by grazing comets or on-going erosion of debris located close to the star, we would expect to find evidence for warm dust in all Beta Pic-like systems. We have carried out detailed studies of the circumstellar environments of all nearby A-type stars. We have studied not only their circumstellar dust but also the characteristics of their circumstellar gas through absorption line spectroscopy. Based on our visible and IUE data, we identified about a dozen A-type stars with circumstellar gas. Among them, 7 have dynamic circumstellar gas similar to that found in the Beta Pic system, but none of them has detectable IRAS infrared excess. What is the origin of the dynamic circumstellar gas around young A-type stars? The STIS wavelength range covers many fine-structure lines that can only be seen at high densities, which are characteristic of circumstellar but not interstellar gas. We propose to observe these 7 stars with STIS to {a} verify the circumstellar gas detections from our previous visible and IUE studies, {b} determine the temperature and electron number density in the circumstellar gas, {c} derive accurate circumstellar gas column densities, and {d} study the possible causes of the variable circumstellar absorption lines {both red-shifted and blue-shifted have been seen in spectra of Beta Pic and our 7 target stars}. ------------------------------------------------------------------------------ Prop. Type: GTO/OS Category: ID: 1022 Cycle: 0 Title: DO GALAXIES PRODUCE QUASAR ABSORPTION LINES? (CYCLE 0) PI: John Bahcall SPECTRA WILL BE OBTAINED WITH THE FOS FOR A NUMBER OF QUASARS SMALL ANGULAR SEPARATION ON THE SKY FROM GALAXIES OR GALAXY V MARK 205, 3C 232, PKS 2020-370, THE GRAVITATIONALLY LENSED QU OBJECTS BEHIND THE BOOTES GALAXY VOID, US 1329 (BEHIND THE BA GALAXY VOID), AND 5C 03.44 (BEHIND M 31). THE SPECTRA WILL BE HYPOTHESIS THAT SOME METALLIC QUASAR ABSORPTION SYSTEMS ARE C LARGE GALAXY HALOS OR DISKS. WF/PC IMAGES WILL ALSO BE OBTAIN GALAXY, 2237+0305, IN ORDER TO LOCATE ACCURATELY THE QUASAR P MEASURE THE SURFACE BRIGHTNESS OF THE INNER REGION OF THE GAL OBSERVATIONS ARE REQUIRED BECAUSE, FOR THE SMALL REDSHIFTS AT WITH LARGE ANGULAR SIZE ARE FOUND, THE RESONANT ATOMIC LINES ULTRAVIOLET. ------------------------------------------------------------------------------ Prop. Type: GO Category: COOL STARS ID: 10220 Cycle: 13 Title: Probing the Nucleosynthesis Products of the First Stars PI: Christopher Sneden We propose the first extensive HST study of Galactic halo stars that are deficient in heavy {i.e., neutron-capture} elements. These so-called r- process-poor stars contain the nucleosynthesis products from the earliest generations of stars, the progenitors of the halo stars. Detections of the lightest neutron-capture elements, such as Ge, along with some of the heaviest, including Pt, can only be obtained in the NUV. Our HST abundance analysis of the well-known bright {r-process-poor} giant star HD 122563 indicates a surprising drop off in neutron-capture element abundances from Ge to Pt. This is in contrast to the solar pattern seen in r-process-rich stars, and suggests that some of the very earliest generations of stars were unable to synthesize the heaviest elements. To confirm and strengthen this finding we will obtain abundance determinations for a number of neutron-capture elements in a target sample of 8 stars, spanning a wide range of metallicity. The resulting abundance distributions will provide a direct indication of the nucleosynthetic conditions {such as temperatures, densities, and neutron fluxes} in the halo progenitors. These in turn will help to identify the characteristics {such as masses and metallicities} and nature of the first stars in the Galaxy. ------------------------------------------------------------------------------ Prop. Type: GO Category: STAR FORMATION ID: 10221 Cycle: 13 Title: Uncovering the unknown Ly-alpha flux in classical T Tauri stars PI: Gregory Herczeg The FUV emission of CTTSs significantly impacts the chemical evolution and aids in the dispersal of gas in protoplanetary disks. Despite its importance, the dominant source of FUV emission, H I Ly-alpha at 1215.67 A, is not directly observable due to neutral hydrogen absorption in our line of sight to nearly all young stars. We have recently developed a novel technique to indirectly measure the Ly-alpha emission incident on the disk using Ly-alpha pumped molecular hydrogen emission lines, which are detected throughout the UV spectra of CTTSs. Measuring the Ly-alpha flux has a large effect of the total FUV emission from CTTSs: results from test cases demonstrate that at least 75% of the FUV emission is in this one line. The lack of accurate measurements of Ly-alpha remains a glaring weakness in chemical models of protoplanetary disks and disk dispersal. This strong emission will create a Ly-alpha dominated PDR-like disk surface at planet-forming radii close to the star. We propose using molecular hydrogen emission to reconstruct the intrinsic Ly-alpha line from three CTTSs to understand the dominant FUV emission source from these stars and its effect on protoplanetary disks. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: GALAXIES ID: 10222 Cycle: 13 Title: The Next Generation Spectral Library PI: David Silva We propose to complete our snapshot program to produce a Next Generation Spectral Library of 600 stars for use in modeling the integrated light of galaxies and clusters. This program is using the low dispersion UV and optical gratings of STIS. The library will be roughly equally divided among four metallicities, very low {[Fe/H] < -1.5}, low {-1.5 < [Fe/H] < -0.5}, near-solar {-0.3 < [Fe/H] < 0.1}, and super-solar {[Fe/H] > 0.2}, well-sampling the entire HR-diagram in each bin. Such a library will surpass all extant compilations and have lasting archival value, well into the Next Generation Space Telescope era. Because of the universal utility and community-broad nature of this venture, we waive the entire proprietary period. ------------------------------------------------------------------------------ Prop. Type: GO Category: QUASAR ABSORPTION LINES/IGM ID: 10223 Cycle: 13 Title: Probing a damped Lyman-alpha system along two lines of sight PI: Nicholas Morgan Damped Lyman-alpha absorption systems hold key information about galaxy formation and chemical evolution of the Universe. We have recently discovered that the bright {V = 15.5} z=1.07 quasar HS 2209+1914 is a gravitationally lensed double with an image separation of 1.0 arcsec and a clearly detected lensing galaxy. A strong Mg II and Fe II absorption systems at z=0.51 is very suggestive of a common damped Ly-alpha absorber {DLA} in both lines of sight, presumably identical with the lensing galaxy. We propose to obtain UV spectroscopy of both QSO components, with the principal aim to confirm the DLA hypothesis and obtain the column density of neutral hydrogen along both lines of sight. This will enable future high-resolution spectroscopy to determine elemental abundances and their spatial variance between different locations in the absorber. In combination with new ground-based deep infrared images, HS 2209+1914 will be the only known DLA galaxy where spatially resolved abundance information can be directly related to the observed distribution of stellar light. Byproducts of our study will include new insights into the lensing geometry of the system, a high S/N measurement of differential extinction through the lensing galaxy, and an estimate of the lensing galaxy's extinction curve. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10224 Cycle: 13 Title: Spatially Resolved mid-UV Spectra of the Centers of Local Group Galaxies PI: Ricardo Schiavon We propose to use STIS to collect medium resolution mid-UV and optical spectra from the nuclei of M31, M32 and NGC 205. The observations will provide fundamental constraints to the stellar population models we are currently developing in our Treasury Program {GO-9455, PI Ruth Peterson}. The data will also be useful to constrain the stellar population content in the centers of the target galaxies. Last but not least, they will be crucial templates for studies of distant galaxies, by providing a direct assessment of spectrophotometric evolution in the mid-UV. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10225 Cycle: 13 Title: Abundances in AGN Outflows: Putting Real Numbers Into Quasar Feedback Scenarios PI: Nahum Arav AGN outflows impact the evolution of supermassive black holes, host galaxies, and the surrounding IGM. To assess the importance of these processes, it is essential to obtain the physical properties of real AGN winds. Our proposed HST/STIS observations of the Seyfert 1 galaxy Mrk 509, in combination with dedicated FUSE time, are designed to obtain the first reliable determination of chemical abundances for an AGN outflow. Previous attempts to measure abundances from outflow absorption troughs did not account for velocity dependent covering factors of the absorbers. This led to large uncertainties in measuring absorption column densities, uncertainties which are magnified when translated to abundances. To extract reliable column densities, we created an array of analysis tools for modeling high-S/N echelle data of doublets and higher multiplet lines from the same ion. After carefully reviewing all the available targets we conclude that the combination of high UV flux and unblended outflow troughs makes Mrk 509 the most promising target for obtaining abundances in AGN outflows. Our proposed Mrk 509 observations will provide the best input to date for accurately modeling the influence of AGN winds on the galactic and inter-galactic environments. ------------------------------------------------------------------------------ Prop. Type: GO/PAR Category: GALAXIES ID: 10226 Cycle: 13 Title: The NICMOS Grism Parallel Survey PI: Matthew Malkan We propose to continue managing the NICMOS pure parallel program. Based on our experience, we are well prepared to make optimal use of the parallel opportunities. The improved sensitivity and efficiency of our observations will substantially increase the number of line-emitting galaxies detected. As our previous work has demonstrated, the most frequently detected line is Halpha at 0.770 AU}; at such large distances around GJ 803, dust evolutionary timescales are longer than the stellar age, and hence we can study the composition of primordial circumstellar material. The combined dataset will provide the most comprehensive study to date of a debris disk from ~7 AU to ~200 AU radius. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10229 Cycle: 13 Title: Space Motions for the Draco and Sextans Dwarf Spheroidal Galaxies PI: Slawomir Piatek We will use the powerful astrometric capabilities of HST to measure proper motions for the Draco and Sextans dwarf spheroidal galaxies that will yield tangential velocities accurate to about 30 km/s. These two galaxies are the last inside a galactocentric radius of 200~kpc without measured proper motions. Knowing their orbits is critical for our understanding of the low-luminosity satellites of the Milky Way. In particular they are critical for understanding why Ursa Minor has survived tidal disruption on its plunging orbit and how Carina formed a large intermediate-age stellar population despite its small mass. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10230 Cycle: 13 Title: Radial Velocity Variability in the Mass Outflow in the Seyfert 1 Galaxy NGC 3783 PI: Jack Gabel We have discovered a decreasing radial velocity in an outflowing UV absorber in NGC 3783 -- the first unambiguous detection of kinematic variability in an AGN outflow. The observed velocity shift could be due either to bulk deceleration of the outflow or a geometric effect, in which the radially projected component of velocity changes as the outflow moves across our line of sight. Several pieces of evidence support the latter interpretation. A simple geometric model of an absorber with a changing velocity vector predicts the absorption line depths will decrease sometime before mid-2005, at an increasingly rapid rate, and eventually disappear. We propose three STIS E140M observations, obtained at 4 -- 8 months intervals, to determine the underlying mechanism causing this rare phenomenon. Specifically, these observations will allow us to: 1} track the radial velocity variations, 2} follow the evolution of the covering factors, thereby mapping the geometry and transverse motion of the absorber against the background AGN light, 3} determine the ionization structure in the outflow by monitoring ionization-dependent coverage, and 4} test for changes in the ionization of the absorber using photoionization models. These results will provide a definitive test of the geometric model, and will place strong limits on alternative mechanisms. In addition, we have also been allocated two FUSE observations of NGC 3783 in the upcoming cycle. We request simultaneous observations in at least one epoch, which will place very tight constraints on the absorption/emission geometry. These results will provide crucial input needed to test dynamical models of AGN outflows. ------------------------------------------------------------------------------ Prop. Type: GO Category: QUASAR ABSORPTION LINES/IGM ID: 10231 Cycle: 13 Title: Tracing the Reionization History of Intergalactic Helium out to Redshift 3.8 PI: Wei Zheng We have found He II absorption in a quasar at redshift 3.82 via our Cycle 12 program of UV snapshots. This is the highest redshift yet at which He II absorption has been observed, and we propose a high S/N STIS follow-on spectrum to study helium ionization in the IGM along this new, long, unobscured sightline to high-redshift. The object has UV flux comparable to that of the rare handful of other z>3 quasars known to be suitable for helium studies, and it is also in the Continuous Viewing Zone, permitting a high-quality STIS spectrum in just 8 HST orbits. The proposed spectrum will allow us to study the evolution and properties of the IGM and ionizing radiation from z=3.8 {the IGM environment near the quasar} all the way down to z=2.8. This redshift range may span the epoch of helium reionization, and even extends to high enough redshift to enable improved helium opacity measures using both He II Ly-alpha and Ly-beta. This program is now approved to use ACS prism. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10232 Cycle: 13 Title: Constraining Models of Galactic Chemical Evolution and Mixing by Measuring the Spatial Variability of D/H in the Interstellar Medium PI: Scott Friedman Measuring the abundance of deuterium relative to hydrogen in the interstellar medium provides a method to assess the effects on the D/H ratio of astration and subsequent chemical enrichment of the ISM by supernovae, massive star winds, infalling gas, and mixing. It is now well established that D/H is approximately constant within the Local Bubble, at distances <~ 100 pc. At greater distances there is limited but growing evidence that it varies. However, confirmation of this, and a more definitive interpretation of the variability, requires improved measurements of the HI column density, which can only come from STIS measurements of the Ly alpha line. We request observations of 7 targets, all well outside the Local Bubble based on their DI column densities, to establish the degree of variability with high confidence. FUSE observations to determine N{DI} are complete for 5 targets, the remaining ~30% of the data on a 6th target is scheduled to be obtained at the end of January, 2004, and the last target is part of an accepted FUSE cycle 5 program. With the improved HI column densities obtained with the observations proposed here, we will confirm the variability indicated by a small number of IMAPS and FUSE sight lines, and we will place important constraints on models of chemical evolution and mixing. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10233 Cycle: 13 Title: Determining the Instability Strip for Accreting White Dwarfs PI: Paula Szkody Using UV observations with SBC and PR110L, we will obtain spectra of 3 newly discovered pulsating white dwarfs found among recent cataclysmic variables identified in the SDSS. Our Cycle 8 observations of the only previously known accreting, pulsating, white dwarf in GW Lib revealed large amplitude UV pulsations, a spectrum that showed metals and required a dual temperature fit with a high white dwarf mass. Since accretion likely causes abundance, rotation, and atmospheric temperature differences in accreting white dwarfs versus single white dwarfs, we will use these systems to explore the location of the instability strip for accreting white dwarfs and determine whether they are all massive and spotted objects. Light curves can be constructed at different wavelengths to aid in mode identification. Having knowledge of the atmospheres and interior structure of 4 sytems will provide great insight into the interaction of accretion, stellar pulsation and long term evolution. Due to optical contamination by the disk, stream, and/or secondary, the UV is the optimum regime to study pulsating, accreting white dwarfs. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10234 Cycle: 13 Title: A search for gamma Cas analogs at low metallicity PI: Luciana Bianchi Extensive studies of Be stars in the Milky Way {MW}, from optical to X-Ray wavelengths, showed that this class of objects gives important clues to our understanding of issues of broad relevance, among them the dynamo mechanism, stellar evolution {single/binary}, circumstellar disks, variability and mechanisms for X-ray emission. Moreover, the classical prototype {from optical studies} of this class, gamma Cas, has turned out to be unique in its X-ray properties. Can we find gamma Cas analogs in other galaxies? How does the Be phenomenon depend on metallicity ? We propose to extend the study of Be stars to the low metallicity Small Magellanic Cloud {SMC}. We selected a small, exploratory but significant, sample of Be stars detected from our extensive ground-based surveys. Because many crucial properties can only be measured in the UV, we propose to obtain STIS UV spectra to complement our data at other wavelengths {ground-based, including light curves and Halpha, and X-rays} , in order to: {1} characterize the SMC counterpart of the Be class, so far only {and extensively} studied in the UltraViolet in the MW, in the parameter space Teff, Lbol, mass loss, and {2} perhaps detect analogs of the hitherto unique object gamma Cas. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10235 Cycle: 13 Title: Dark vs. luminous matter in the CenA/M83 galaxy complex PI: Igor Karachentsev The distribution of dark vs. luminous matter on scales of 0.1-1.0 Mpc remains poorly understood. For a nearby group, the total mass can be determined from the radius of "the zero-velocity surface", which separates the group from the general Hubble flow. This new method requires the measurement of accurate distances and radial velocities of galaxies around the group, but gives total mass estimates independent of assumptions about the state of relaxation or orbital characteristics. The mass pertains to the group at the full scale to which it is bound. Upon application in several nearest groups, the method yields mass estimates in agreement with the sum of the virial masses of subcomponents. However, the typical total M/L ratio for the nearby groups of ~30 Mo/Lo implies a local mean density of matter which is only 1/7 the canonical global density . The nearby complex of galaxies around Cen A and M83 resembles our Local Group by the dumb-bell concentration of objects around a pair of dominant galaxies. Accurate distances have been acquired recently for ~20 group members by the TRGB method using HST. We will measure TRGB distances to the 17 remaining galaxies in the region. These observations will constrain the dynamical state of the halo surrounding the nearest giant E-galaxy Cen A, providing a comparison with the halos of the nearest spirals. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: ISM ID: 10236 Cycle: 13 Title: A SNAPSHOT Survey of the Local Interstellar Medium: New NUV Observations of Stars with Archived FUV Observations PI: Seth Redfield We propose to obtain high-resolution STIS E230H SNAP observations of MgII and FeII interstellar absorption lines toward stars within 100 parsecs that already have moderate or high-resolution far-UV {FUV}, 900-1700 A, observations available in the MAST Archive. Fundamental properties, such as temperature, turbulence, ionization, abundances, and depletions of gas in the local interstellar medium {LISM} can be measured by coupling such observations. Due to the wide spectral range of STIS, observations to study nearby stars also contain important data about the LISM embedded within their spectra. However, unlocking this information from the intrinsically broad and often saturated FUV absorption lines of low-mass ions, {DI, CII, NI, OI}, requires first understanding the kinematic structure of the gas along the line of sight. This can be achieved with high resolution spectra of high-mass ions, {FeII, MgII}, which have narrow absorption lines, and can resolve each individual velocity component {interstellar cloud}. By obtaining short {~10 minute} E230H observations of FeII and MgII, for stars that already have moderate or high-resolution FUV spectra, we can increase the sample of LISM measurements, and thereby expand our knowledge of the physical properties of the gas in our galactic neighborhood. STIS is the only instrument capable of obtaining the required high resolution data now or in the foreseeable future. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10237 Cycle: 13 Title: Low-Ionization BALs: Evolution or Orientation? PI: Xiaohui Fan We propose to test the hypothesis that Low-Ionization Broad Absorption Line Quasars {LoBALs} represent a special stage of quasar evolution: young quasars in systems with strong interaction and star-formation. We will carry out high resolution imaging using ACS/WFC and NICMOS to measure the properties of the host galaxies of four LoBAL quasars at z = 0.9 - 2.0 that show strong overlapping FeII absorption troughs. The ACS imaging will be carried out in the passband with the strongest BAL absorption, acting as a natural coronagraph. This results in a reduction of quasar light by a factor of 15 - 26 in these passbands, providing arguably the best view of the host galaxies of luminous, high-redshift quasars. This method allows efficient detection and detailed modeling of the host galaxy morphology in the rest-frame ultraviolet, which is most sensitive to star formation and galaxy interaction. We will also use NICMOS imaging to measure the rest-frame light from the host galaxy to probe the old stellar populations where the host galaxy is likely to be brighter. It has been suggested that LoBALs might not be explained simply as an orientation effect but rather as an early phase of quasar evolution. Such a phase is typically associated with large amounts of dust and gas, and young galaxies with strong star formation. With HST observations, we will study the color and morphology of the FeLoBAL quasar host galaxies, and measure the age of their dominant stellar populations. We will also measure the density of close companions, and, in particular, look for signs of ongoing or recent mergers. These measurements will be compared to those of control samples of normal quasars at similar redshift. If LoBALs are indeed young systems, then their host galaxies are expected to show stronger interactions and merger activity, younger stellar ages, and regions with strong star formation. If the LoBAL host galaxies show no significant difference from those of normal quasars, it will support the view that LoBAL quasars are not a distinct population and that all quasars have BAL outflows along some lines of sight. ------------------------------------------------------------------------------ Prop. Type: GO Category: AGN/QUASARS ID: 10238 Cycle: 13 Title: The nature of quasar host galaxies: combining ACS imaging and VLT Integral Field Spectroscopy. PI: Frederic Courbin We propose to perform ACS/F606W imaging of a complete sample of 29 quasar host galaxies {0.08~ 10% solar} extending up to 50 or even 100 kpc. These data will also allow us to determine some simple kinematics for this halo gas. The edge-on Sc galaxy ESO 157-G049 and the triple system of bright QSOs that all probe its halo within a projected distance of 125 kpc is unique - we have searched the entire sky for bright QSOs within 150 kpc of nearby galaxies and no other nearby galaxies are probed by three QSOs bright enough to be observed with HST/STIS. Our Cycle 11 snapshot program has measured accurate far-UV fluxes for these QSOs and has already made probable detections of Ly-alpha absorption associated with this galaxy in 2 of the QSO sight lines. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: STELLAR POPULATIONS ID: 10255 Cycle: 13 Title: A Never Before Explored Phase Space: Resolving Close White Dwarf / Red Dwarf Binaries PI: Donald Hoard We propose an ACS Snapshot imaging survey to resolve a well-defined sample of highly probable white dwarf plus red dwarf close binaries. These candidates were selected from a search for white dwarfs with infrared excess from the 2MASS database. They represent unresolved systems {separations less than approximately 2" in the 2MASS images} and are distributed over the whole sky. Our HST+ACS observations will be sensitive to a separation range {1-20 AU} never before probed by any means. The proposed study will be the first empirical test of binary star parameters in the post-AGB phase, and cannot be accomplished from the ground. By resolving as few as 20 of our ~100 targets with HST, we will be able to characterize the distribution of orbital semi-major axes and secondary star masses. ------------------------------------------------------------------------------ Prop. Type: GO Category: QUASAR ABSORPTION LINES/IGM ID: 10256 Cycle: 13 Title: Doubling the Data on the HeII Re-ionization of the Intergalactic Medium PI: David Tytler We propose to double the existing information on the ionization of HeII in the IGM at redshifts around 3. We will observe 3 QSOs that are bright in the far UV. Each will give a moderate resolution HST spectrum better than any obtained so far. We will also observe a fourth QSO that currently lacks high SNR spectra. This program addresses a central issue in cosmology: the reionization of the intergalactic medium {IGM}. Current theoretical models predict that H I starts to reionize around z=17, completing near 6, while HeII reionization is delayed until z=3. The theoretical models of the ionization of HeII in the IGM now offer more detailed predictions that the data can distinguish. The new spectra will provide the data required to distinguish between different reionization scenarios, by increasing the number of lines of sight near z=3 with good spectra from 3 to 7, 3 of which will have the best sensitivity to the HeII optical depth. For the first time we also explore the 3-dimensional distribution of the ionizing regions, to characterize the luminosity and number density of the ionizing sources. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10257 Cycle: 13 Title: Astrometric and Photometric Study of NGC 6397 for Internal Motions, Dark Binaries, and X-Ray Sources PI: Jay Anderson We propose to observe the central regions of the globular cluster NGC 6397 with ACS/WFC once per month for the 10 months of its visibility in Cycle 13. The project has three main goals: {1} Measure internal motions for roughly 3000 stars within 150 arcseconds of the cluster center, using archival WFPC2 as a first epoch. The motion of the typical star will be measured to 10-20%. We will detect any central black hole {BH} with a mass greater than 1000 solar masses, and will also measure core-collapse signatures such as anisotropy. {2} Conduct the first-ever search for heavy binaries by looking for the astrometric "wobble" of the luminous secondary. We should find all heavy binaries in the field with separations between 1 and 5 AU and periods between 3 months and 5 years. {3} Search for opticall counterparts to X-ray sources found by Chandra. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10258 Cycle: 13 Title: Tracing the Emergence of the Hubble Sequence Among the Most Luminous and Massive Galaxies PI: Claudia Kretchmer There is mounting evidence that the redshift range 1 < z < 2 was an important era when massive galaxies assembled their stellar content and assumed their present--day morphologies. Despite extensive HST imaging surveys, however, there is very little data in the optical rest frame {i.e., observed near--infrared} on the morphologies of the most luminous galaxies at these redshifts. We propose to image a carefully selected set of 20 of the most luminous, K--band selected GOODS galaxies at 1.3 < z < 2, using NICMOS camera 2. This offers diffraction--limited, critically sampled imaging at 1.6 microns to ensure the best angular resolution for comparison to ACS. The galaxies are chosen to span a simple 4--fold parameter space of morphological and spectral type, in order to provide the most information about the variety of massive galaxy properties in this redshift range. We will investigate the emergence of large scale--length disks, stable spiral structure, mature bulges with red stellar populations, central bar structures, the incidence of disturbed morphology, the existence {or lack thereof} of blue ellipticals, and other questions that concern the evolution and maturation of the brightest, largest, and most massive ordinary galaxies in this critical redshift range. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10259 Cycle: 13 Title: Planetary nebulae in the SMC: a study of stellar evolution and populations in an extremely low-metallicity environment PI: Letizia Stanghellini The final phase of the evolution of low- and intermediate-mass stars, the planetary nebula {PN} ejection, is thought to largely contribute to the carbon and nitrogen enrichment in galaxies, in particular in old stellar populations. Stellar generations forming from a carbon- and nitrogen-enriched medium are a necessary condition for planetary and life formation. It is essential to understand how stars go through the process of shedding their chemically-enriched shells, and to test the predictions of stellar evolution theory on the relationship between stellar mass and elemental enrichment. Magellanic Cloud PNs are ideal probes for this study. Their abundances can be directly related to the mass of the central stars and to that of the stellar progenitor, without the great {distance and reddening} uncertainties that affect Galactic PNs. The UV lines are essential for calculating the abundances of the element related to stellar evolution {C, N, O} and to progenitor populations {e.g., Ne}. We propose to acquire STIS UV spectroscopy of the SMC PNs whose morphology and central star properties has been previously determined by us with HST. We will derive the {C, N, O} abundance-to-mass relation, and determine the extent to which the mass of the progenitors of asymmetric PNs exceed that of symmetric PNs. We will also test the PN luminosity function, and probe cosmic recycling, in a very low-metallicity environment. ------------------------------------------------------------------------------ Prop. Type: GTO/FOS Category: ID: 1026 Cycle: 0 Title: UV SPECTRA OF LOW-REDSHIFT-QSOS (FOS-1) -- CYCLE 0 PI: Margaret Burbidge Three main scientific goals are to determine the emission-line properties in the UV of low-z QSOs, to look for L alpha -forest absorption shortward of L alpha emission to examine evolutionary effects, and to observe L alpha absorption in QSOs which have known metallic-line narrow absorption-line systems at z(absorption) << z(emission). There are objects of special interest included in the sample (e.g. 1548 + 114 A, B). ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10260 Cycle: 13 Title: The Most Massive Star Clusters: Supermassive Globular Clusters or Dwarf Galaxy Nuclei? PI: William Harris Evidence is mounting that the most massive globular clusters, such as Omega Centauri and M31-G1, may be related to the recently discovered "Ultra-Compact Dwarfs" and the dense nuclei of dE, N galaxies. However, no systematic imaging investigation of these supermassive globular clusters -- at the level of Omega Cen and beyond -- has been done, and we do not know what fraction of them might bear the signatures {such as large effective radii or tidal tails} of having originated as dE nuclei. We propose to use the ACS/WFC to obtain deep images of 18 such clusters in NGC 5128 and M31, the two nearest rich globular cluster systems. These globulars are the richest star clusters that can be found in nature, the biggest of them reaching 10^7 Solar masses, and they are likely to represent the results of star formation under the densest and most extreme conditions known. Using the profiles of the clusters including their faint outer envelopes, we will carry out state-of-the-art dynamical modelling of their structures, and look for any clear evidence which would indicate that they are associated with stripped satellites. This study will build on our previous work with STIS and WFPC2 imaging designed to study the 'Fundamental Plane' of globular clusters. When our new work is combined with Archival WFPC2, STIS, and ACS material, we will also be able to construct the definitive mapping of the Fundamental Plane of globular clusters at its uppermost mass range, and confirm whether or not the UCD and dE, N objects occupy a different structural parameter space. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10261 Cycle: 13 Title: The Formation Mechanisms of Extreme Horizontal Branch Stars PI: Thomas Brown We propose far-UV spectroscopy of NGC 2808, in order to better understand the formation mechanisms for extreme horizontal branch {EHB} stars. Our recent analysis of STIS UV imaging has revealed an unusual population of subluminous EHB stars in this cluster, an anomaly that is unexplained by canonical stellar evolution theory. Using new theoretical models of evolution, atmospheres, and spectra, we have demonstrated that these subluminous stars could be the product of a late helium core flash, which occurs while the stars are on the white dwarf cooling curve. The convection zone produced by such a flash will penetrate the hydrogen envelope, mixing hydrogen into the hot helium-burning interior, where it is rapidly consumed. The resulting EHB star would exhibit greatly enhanced helium and carbon at its surface, and would appear subluminous in the UV. Furthermore, the dichotomy between the normal EHB stars and the hotter flash-mixed EHB stars would explain the hottest gap observed in the HB distribution of NGC 2808. Far-UV spectroscopy of normal and subluminous EHB stars in this cluster will unambiguously test this new formation mechanism. The results will also advance our understanding of abundance anomalies in subdwarf B and O stars, the UV emission from elliptical galaxies, and the "born again" scenario for producing hydrogen-deficient R CrB stars. ------------------------------------------------------------------------------ Prop. Type: GO Category: COOL STARS ID: 10262 Cycle: 13 Title: The 3D Morphology of the Extreme Red Supergiant VY CMa PI: Roberta Humphreys The extreme RSG and powerful OH/IR source VY CMa is surrounded by an asymmetric reflection nebula dominated by a prominent nebulous arc, bright filamentary arcs, and several clumps of dusty knots that are evidence for multiple and asymmetric mass loss events. Our groundbased velocities show that these structures are kinematically distinct from the gneral flow of the diffuse gas and may be directional. We have speculated that these arcs and knots may be caused by localized activity on the star involving convection and possibly magnetic fields analogous to lower mass stars. If correct this would have important implications for the causes of high mass loss events in evolved massive stars. Fortunately, VY CMa provides us with an opportunity to learn more about its possible mass loss mechanisms and history from the morphology of its ejecta. We propose to use polarimetry and second epoch images combined with our radial velocities to map the morphology of the nebula and the discrete structures embedded in it. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10263 Cycle: 13 Title: SAINTS - Supernova 1987A INTensive Survey PI: Robert Kirshner SAINTS is a program to observe SN 1987A, the brightest supernova in 383 years, as it transforms into supernova remnant {SNR} 1987A, the youngest supernova remnant. HST is the unique and perfect match in scale and in field for spatially-resolved observations of SN 1987A. Rapid changes are taking place in a violent encounter between the fastest-moving debris and the circumstellar ring. This one-time-only event, leading to suddenly appearing hotspots and new emission that can reveal previously hidden gas, is powered by shocks that can be studied simultaneously with HST and with Chandra to great advantage. Both the optical and X-ray flux from the ring are rising rapidly so prompt observations are needed in Cycle 13. Our previous observations reveal a remarkable reverse shock moving upstream through the expanding debris. The reverse shock provides a powerful tool for dissecting the radial structure of the vanished star. The debris from the explosion itself, still excited by radioactivity, is now well resolved by ACS and seen to be aspherical, providing direct clues to the mechanism of the explosion. Many questions about SN 1987A remain unanswered. SAINTS is a comprehensive attempt to use HST to establish the facts of SN 1987A, help to answer interesting questions, and to observe the birth of SNR 1987A. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10264 Cycle: 13 Title: Observing the Next Nearby Supernova PI: John Bahcall If a neutrino-producing supernova {SN} explodes in the Galaxy, the Large or Small Magellanic Clouds, or a close member of the Local Group, it will be detected first by operating neutrino experiments: Super-Kamiokande, SNO, MACRO, and AMANDA. The supernova neutrino early warning system will notify photon observers throughout the world within an hour of the neutrino detection. Although the per-year probability of observing a neutrino SN {within 100 kpc} is small, the detection would be importantly scientifically and of widespread interest. The optical counterpart could be much brighter than normal extragalactic SNe. A bright nearby supernova detected by other means would also be of great interest and should activate this proposal. We propose unique STIS ultraviolet spectroscopic observations to measure the principal metallic lines, and hence the composition, velocity, and physical state, of the outermost atmosphere of the exploded star. In addition, we propose narrow- and broad-band imaging to provide information about the stellar environment and early morphology unobtainable from the ground. The data, especially images, will be valuable for public outreach and will be released immediately by NASA. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10265 Cycle: 13 Title: The Formation History of Andromeda PI: Thomas Brown We propose deep observations of Andromeda's outer disk and giant tidal stream, to reconstruct their star formation histories. As the nearest giant galaxy, Andromeda offers the best testing ground for understanding galaxy formation and evolution. Given the dramatic increase in sensitivity offered by the ACS, we can now resolve stars on the old main sequence in the other giant spiral of the Local Group, and employ the same direct age diagnostics that have been used for decades in the study of Galactic globular clusters. In Cycle 11, we successfully observed a field in the Andromeda halo and constructed a deep color-magnitude diagram reaching well below the oldest main sequence turnoff. In Cycle 13, we propose to extend these observations to the outer disk and tidal stream of Andromeda, to constrain their star formation histories and compare them to that of the halo. The combined observations from these two programs will offer a dramatic advance in our understanding of the overall evolution of spiral galaxies. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10266 Cycle: 13 Title: Origins of the Highly Ionized Gas toward the X-ray Bright BL Lac Object Mrk 421 PI: Blair Savage The X-ray bright BL Lac object Mrk 421 is one of the small number of extragalactic objects for which it is possible to study the highly ionized gas in the ISM and Local Group using the full diagnostic power of UV, far-UV and X-ray observatories. High quality far-UV observations of OVI and other ions have been obtained by FUSE, whereas Chandra and XMM-Newton have provided X-ray measurements of extremely strong OVII and OVIII absorption at redshift zero. It has been proposed that the OVI, OVII, and OVIII originate together in the warm-hot intergalactic medium, of the kind predicted by numerical simulations to contain a substantial fraction of the baryons at z=0. However, the properties of the high-ion absorption are also consistent with an origin in an extended Galactic Corona. Data for other species such as SiIII, SiIV, and CIV will be essential to determine whether or not a Local Group WHIM filament has been detected. These species are not expected to be seen in a hot {T > 10^6 K} medium and their detection at the same velocity as OVI would suggest that the OVI samples a different phase of the gas than the OVII and OVIII. We propose to obtain a high quality 7 km/s resolution STIS UV spectrum of Mrk 421 from 1150 to 1700 A. The STIS measurements of CII, CIV, SiIII, SiIV, and other species will allow us to evaluate the ionization conditions in the absorbing gas in the Galactic thick disk and in an anomalous high positive velocity absorption wing currently only traced by OVI and CIII. The ionic ratios among these species will provide critical tests of the ionization mechanisms affecting the OVI absorption. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10267 Cycle: 13 Title: The Shadow Echoes of the Unique R Coronae Borealis Star, UW Cen PI: Geoffrey Clayton Understanding the R Coronae Borealis {RCB} stars is a key test for any theory aiming to explain hydrogen deficiency in post-AGB stars. The RCB stars are rare hydrogen-deficient carbon-rich supergiants that undergo very spectacular declines in brightness of up to 8 magnitudes at irregular intervals as dust forms near the star along the line of sight. UW Cen is unique among the cool RCB stars in having a visible circumstellar shell. The morphology of the nebula appears to change as different parts are illuminated by light from the central star modulated by shifting, thick dust clouds near its surface. The central star acts like a "lighthouse, " shining through gaps between the near-star dust clouds, and lighting up different portions of the outer nebula. We propose a scientific program in which a small number of observations using ACS/HRC will exploit UW Cen's unique circumstellar shell to address two critical elements in understanding RCB stars: determining an accurate distance to the star, and studying the otherwise unobservable dust clouds forming near the star's surface. We will model the images using Monte Carlo techniques to calculate the radiative transfer through arbitrary distributions of dust viewed from any angle. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10268 Cycle: 13 Title: Recovery of three faint Kuiper Belt Objects discovered with HST PI: David Trilling We propose 6 orbits to make ACS/WFC follow-up observations of three faint Kuiper Belt Objects {KBOs} that we discovered in the Large Cycle 11 program GO 9433 {G. Bernstein, PI; Bernstein et al. 2004}. These KBOs are the faintest -- and therefore smallest -- KBOs known. Two of these objects can be recovered {and the third easily recovered and its colors probed} only with HST. Any future studies of small KBOs will require knowledge of our three faint KBOs. With the proposed observations, the locations of these KBOs will be known quite well until after first light for JWST. Without the proposed observations, these three small KBOs will be effectively lost. This small program represents a small investment of HST time to solidify the legacy of the Bernstein et al. Large GO program. With the proposed observations, we will be able to determine with certainty the dynamical classes of these three KBOs, testing the hypothesis that small KBOs are predominantly classical KBOs. We will also test the suggestion that classical KBOs are uniformly quite red. Lastly, our observations will enable physical studies {e.g., spectroscopy} with JWST a decade from now. All these measurements will provide important evidence for theories on the formation and evolution of the Solar System. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10269 Cycle: 13 Title: The Relative Roles of Volcanism and Sublimation in Supporting Io's Atmosphere PI: John Spencer We propose disk-resolved 2000-3150 A spectroscopy of Io's unique SO2 atmosphere in order to test the relative importance of volcanism and frost sublimation in supporting the atmosphere. This is important for answering such basic questions as the extent to which the atmosphere collapses at night. If it does collapse, it is the only substantial atmosphere in the solar system to behave in this manner. Our observations will target low-latitude regions away from active plumes {in contrast to our Cycle 10 observations which targeted the Prometheus plume}, to look for the effect of plumes on the atmosphere. We will also look at the variation of low-latitude atmospheric abundance with terrain type, to look for explanations for the large longitudinal variations in atmospheric pressure seen in earlier data. Finally, we will look at a variety of regions at two different times of day to determine the extent of diurnal variations in the atmosphere, which are expected if the atmosphere is dominantly supported by frost sublimation. ------------------------------------------------------------------------------ Prop. Type: GTO/FOS Category: ID: 1027 Cycle: 0 Title: UV SPECTRA OF QSOS WITH Z > 3.1: CYCLE 0 OBSERVATIONS PI: Margaret Burbidge Observe for the first time the extreme UV rest spectrum of QSOs with z > 3.1, to examine HeI and HeII in absorption and/or emission; perform Gunn-Peterson test for smooth intergalactic helium, determine and compare density of Lyman alpha forests of narrow absorptions per unit z; look for correlations of strongest narrow Lyman alpha absorptions with narrow helium absorptions; look for associated or intervening galaxies. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10270 Cycle: 13 Title: Titan : Huygens Probe Entry Fireball and UV Seasonal Change PI: Ralph Lorenz We plan a single-orbit observation of Titan to observe the 387nm CN emission associated with the entry fireball of the ESA Huygens probe into Titan's methane-rich nitrogen atmosphere. The observation may confirm the entry time of the probe, and provide constraints on the nonthermal emission from the shock layer and wake for an entry body of known ballistic parameters to aid aerothermodynamic models to aid meteoric studies and future heat shield designs. Whether the entry is detected or not, the observation also yields a north-south spectral profile to diagnose the continuing seasonal change on Titan, namely the north-south seasonal asymmetry, and the disappearing UV-dark south polar hood. Near-IR STIS Spectra, nominally before and after the probe entry, will constrain the stratospheric and tropospheric haze and cloud structure, for future comparison with probe data, as well as indicate any changes during the entry. ------------------------------------------------------------------------------ Prop. Type: GO Category: HOT STARS ID: 10271 Cycle: 13 Title: IY UMa: A literal probe of accretion disc structure PI: Carole Haswell IY UMa is a recently-discovered double-lined eclipsing CV with an extremely high inclination. The orientation allows us a view into a narrow shock-heated cavity driven into the disc edge by the accretion stream from the mass donor star. This {literal} probe is so far unique. At the orbital phase when we look into the hot cavity, the emission from the cavity should be a significant fraction of the total UV flux. Comparison with our hydrodynamic simulations of the stream-disc impact will allow us to determine the structure of the cool quiescent outer disc. We will fully characterise the white dwarf, measuring its rotation rate, surface gravity, effective temperature, chemical abundances, accretion rate and gravitational redshift. The obscuration of the inner UV emitting regions by vertical structure associated with spiral density waves will be measured and interpreted by comparison with our simulations. The observations will be performed in the CVZ. ------------------------------------------------------------------------------ Prop. Type: SNAP Category: STELLAR POPULATIONS ID: 10272 Cycle: 13 Title: A Snapshot Survey of the Sites of Recent, Nearby Supernovae PI: Alex Filippenko During the past few years, robotic {or nearly robotic} searches for supernovae {SNe}, most notably our Lick Observatory Supernova Search {LOSS}, have found hundreds of SNe, many of them in quite nearby galaxies {cz < 4000 km/s}. Most of the objects were discovered before maximum brightness, and have follow-up photometry and spectroscopy; they include some of the best-studied SNe to date. We propose to conduct a snapshot imaging survey of the sites of some of these nearby objects, to obtain late-time photometry that {through the shape of the light and color curves} will help reveal the origin of their lingering energy. The images will also provide high-resolution information on the local environment of SNe that are far superior to what we can procure from the ground. For example, we will obtain color-color and color-magnitude diagrams of stars in these SN sites, to determine their progenitor masses and constraints on the reddening. Recovery of the SNe in the new HST images will also allow us to actually pinpoint their progenitor stars in cases where pre-explosion images exist in the HST archive. Use of ACS rather than WFPC2 will make our snapshot survey even more valuable than our Cycle 9 survey. This Proposal is complementary to our Cycle 13 archival proposal, in which we outline a plan for using existing HST images to glean information about SN environments. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10273 Cycle: 13 Title: Accurately Mapping M31's Microlensing Population PI: Arlin Crotts We propose to augment an existing microlensing survey of M31 with source identifications provided by a modest amount of ACS {and WFPC2 parallel} observations to yield an accurate measurement of the masses responsible for microlensing in M31, and presumably much of its dark matter. The main benefit of these data is the determination of the physical {or "einstein"} timescale of each microlensing event, rather than an effective {"FWHM"} timescale, allowing masses to be determined more than twice as accurately as without HST data. The einstein timescale is the ratio of the lensing cross-sectional radius and relative velocities. Velocities are known from kinematics, and the cross-section is directly proportional to the {unknown} lensing mass. We cannot easily measure these quantities without knowing the amplification, hence the baseline magnitude, which requires the resolution of HST to find the source star. This makes a crucial difference because M31 lens m ass determinations can be more accurate than those towards the Magellanic Clouds through our Galaxy's halo {for the same number of microlensing events} due to the better constrained geometry in the M31 microlensing situation. Furthermore, our larger survey, just completed, should yield at least 100 M31 microlensing events, more than any Magellanic survey. A small amount of ACS+WFPC2 imaging will deliver the potential of this large database {about 350 nights}. For the whole survey {and a delta-function mass distribution} the mass error should approach only about 15%, or about 6% error in slope for a power-law distribution. These results will better allow us to pinpoint the lens halo fraction, and the shape of the halo lens spatial distribution, and allow generalization/comparison of the nature of halo dark matter in spiral galaxies. In addition, we will be able to establish the baseline magnitude for about 50, 000 variable stars, as well as measure an unprecedentedly deta iled color-magnitude diagram and luminosity function over much of M31. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM ID: 10274 Cycle: 13 Title: Prospecting for Rare Elements in the Interstellar Medium PI: James Lauroesch The complex history and evolution of element production is reflected in the abundance ratios of the elements. The distinctive abundances patterns produced by nucleosynthesis in supernovae and stars can be used to explore the history of star formation and evolution in galaxies. Recent observations of damped Lyman-alpha systems have suggested that observations of r and s-process elements at high redshifts may soon provide a new window to explore chemical evolution. Paradoxically, we may soon have more detections of some elements in the interstellar medium of these high redshift galaxies than in the Galactic ISM. However, without an understanding of the depletion behavior of these elements based upon observations of nearby sightlines we may be unable to correctly disentangle the effects of dust depletion and nucleosynthesis. We therefore propose to determine the depletion of r and s-process elements in two sightlines with relatively mild depletion patterns on nearly opposite parts of the sky. In addition to providing a baseline for studies at high redshift, the long pathlength studied will enable us to search for abundance variations within our Galaxy. ------------------------------------------------------------------------------ Prop. Type: GO Category: SOLAR SYSTEM ID: 10275 Cycle: 13 Title: The Moons, Rings and Arcs of Uranus: Discovery and Dynamics PI: Mark Showalter Last year, our Uranian ring and moon observing program {GO-9823} resulted in the discovery of two moons, S/2003 U 1 and S/2003 U 2. We imaged two additional small moons, Ophelia and S/1986 U 10, that had not been seen since the Voyager encounter of 1986. Furthermore, our data show faint arcs and clumps orbiting within the rings, which were not seen by Voyager and are completely unexpected. We employed several "tricks" of the HRC to achieve this remarkable senstivity; specifically, we used the CLEAR filter and oriented the images so that the planet, though vastly overexposed, did not interfere with the ring/moon region of interest to us. This allowed us to detect 25th-magnitude moons circling a 5th-magnitude planet. Now we propose to complete the task by carrying out a comprehensive survey of the system using the same techniques. Our goals are to recover the moons, better discern their orbital elements, and learn more about the dynamics of the ring clumps. In particular, we need to {1} understand the long-term stability of S/2003 U 2, which orbits perilously close to the larger moon Belinda; {2} complete our search for moons, which was only ~ 50% complete last year, and {3} better understand how the clumps and arcs within the ring system might relate to nearby "shepherding" moons, seen or unseen. ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10276 Cycle: 13 Title: Resolving Distance Ambiguity toward Westerlund 2 PI: Henry Kobulnicky See original {APT crapped out and won't load my old .apt files} ------------------------------------------------------------------------------ Prop. Type: GO Category: STELLAR POPULATIONS ID: 10277 Cycle: 13 Title: Ages and Metallicities of the Intergalactic Globular Cluster Population in Abell 1185 PI: Michael West We will obtain deep NICMOS observations of a recently discovered population of intergalactic globular clusters in the nearby galaxy cluster Abell 1185. These H band observations in conjunction with deep V and I images that we obtained with ACS in Cycle 11 will allow us to measure the ages and metallicities of these objects from their optical and near-infrared colors, which will provide important insights to their origin. We will also obtain parallel observations with both ACS and WFPC2. ACS parallel observations will be used to obtain deep images to search for intergalactic globular clusters in a different region of Abell 1185. WFPC2 parallel observations will be used to obtain images of interacting galaxy pair Arp 105, to search for globular clusters currently being ejected into intergalactic space as a result of this encounter. ------------------------------------------------------------------------------ Prop. Type: GO Category: QUASAR ABSORPTION LINES/IGM ID: 10278 Cycle: 13 Title: Probing the Outer Regions of M31 with QSO Absorption Lines PI: David Turnshek We propose HST-STIS-UV spectroscopy of 10 recently-discovered quasars behind M31. Absorption lines due to MgII and FeII will be searched for and measured. Six quasars lie between 1 and 4.2 Holmberg radii near the major axis on the southwest side, where confusion with Milky Way gas is minimized. Two lie even farther out on the southwest side of the major axis. One lies within 1 Holmberg radius. Two of the 10 pass through M31's high velocity clouds recently seen in a detailed 21 cm emission map. Thus, using the most well-studied external spiral galaxy in the sky, our observations will permit us to check, better than ever before, the standard picture that quasar metal-line absorption systems arise in an extended gaseous halo/disk of a galaxy well beyond its observable optical radius. Notably, the observations have the potential of extending M31's rotation curve to very large galactocentric distances, thereby placing new constraints on M31's dark matter halo. ------------------------------------------------------------------------------ Prop. Type: AR Category: ISM ID: 10279 Cycle: 13 Title: A Comprehensive Study of Interstellar Depletions PI: Edward Jenkins We propose to analyze interstellar gas-phase abundances of Ga, Sn, Pb, B, S by measuring their absorption features in the spectra of stars observed in SNAP survey programs 8241, 8662 and 9434 {plus other programs that have had archive data released to the public}. The lines of Pb II and B II are extremely weak, so stars will be grouped into cases having different levels of general depletion and then within each category the spectra will be coadded to enhance the detectability of the lines. These data will be combined with results derived by S. Cartledge and coworkers on O and Kr, plus data soon to be published for Ge, Cu, Mg, Mn, Ni and P, in order to understand the general behavior of depletions of atoms onto dust grains under different conditions, using a new analysis technique developed by Jenkins {2003}. A better knowledge of the systematics of depletions will be beneficial to studies of the compositions of dust grains and will also aid investigations of total element abundances in distant damped L-alpha {DLA} systems seen in the spectra of quasars recorded by ground-based telescopes. ------------------------------------------------------------------------------ Prop. Type: AR Category: ISM ID: 10280 Cycle: 13 Title: Fundamental Properties of Gas in the Distant Galactic Halo and Leading Arm of the Magellanic Stream PI: Todd Tripp We propose to use high-resolution archival STIS echelle spectra of a cloud that is located in the Magellanic Stream, and therefore at a distance of ~50 kpc, to obtain detailed observational constraints on the density, pressure, temperature, and ionization structure of gas in the leading arm of the Magellanic Stream. Since this cloud is known to be pressure-confined by the surrounding halo gas, the results will have implications for the physical conditions of the Galactic halo as well. We will apply the following diagnostics to the absorption lines in archival STIS spectra: {1} thermal pressure from C I fine-structure excitation, {2} density constraints from C II*, {3} electron density and temperature from ionization balance, and {4} ionization structure and density constraints from photoionization models. With these physical conditions measurements, we will learn about the nature of O VII and high-velocity O VI absorbers, the evolution of satellite galaxies that pass close to the Milky Way, and whether theoretical work on the ISM in the Milky Way halo agrees with observations. We will also learn about production/destruction of molecular hydrogen in conditions similar to the high-z conditions in which early stars formed. ------------------------------------------------------------------------------ Prop. Type: AR Category: STELLAR POPULATIONS ID: 10281 Cycle: 13 Title: Evolution of Stars and Stellar Systems. I. The Initial Size Distribution of Clusters PI: Rupali Chandar There are three fundamental properties which define a star cluster -- age, mass, and size. While much attention has been focused on the first two parameters, significantly less is known concerning not only actual cluster sizes and structures, but the initial distribution of stellar clustering which occurs in different environments. For example, NGC 1569 has formed three compact, massive young clusters in the last 10 Myr, while IZw18 appears to have only formed more diffuse, "scaled up" OB associations {SOBAs}. The HST archive now contains sufficient observations of nearby star-forming galaxies to allow a quantitative measure of the initial clustering of star formation. We propose to measure the distribution of the physical scales of cluster formation, from the most compact clusters to diffuse SOBAs in 30 nearby galaxies. Local variations in the star formation rate may manifest themselves in the fraction of star formation occuring in compact clusters vs. that occurring in more diffuse OB associations. Because our galaxy sample covers a large range in environment, mass, and star formation rate density, we will take the next step, and use our size distributions to place constraints on the processes responsible for setting the scales of star formation in the local universe. A complementary proposal aims to study the isolated red supergiant population in nearby star-forming galaxies {PI: Dr. C. Leitherer}. ------------------------------------------------------------------------------ Prop. Type: AR Category: QUASAR ABSORPTION LINES/IGM ID: 10282 Cycle: 13 Title: Discovery of two Star-Forming Galaxies causing strong Quasar Absorption Lines PI: Regina Schulte-Ladbeck We have positionally matched our database of over 19, 000 star-forming galaxies {SFGs} from the Sloan Digital Sky Survey {SDSS} against the SDSS QSO catalog. This has allowed us to discover nineteen bright QSOs with redshifts of less than or about one behind local SFGs. Two of the QSOs were fortuitously already observed with HST, and show strong Lyman alpha lines at the emission-line redshifts of the SFGs ------------------------------------------------------------------------------ Prop. Type: AR Category: COSMOLOGY ID: 10283 Cycle: 13 Title: Confronting HST Observations of Dwarf Spheroidals with Theory PI: Nickolay Gnedin We will continue our work on using advanced cosmological simulations to model the formation and evolution of dwarfs spheroidal galaxies. Our previous simulations were able to fully resolve the internal structure of dwarf spheroidals formed before the reionization epoch. In this cycle we will incorporate results from our previous simulations into a large-scale N-body only code to model the formation of the Local Group and to relate the results of our gas-dynamical simulations to the present distribution of dwarf spheroidals in the Local Group. The results of our simulations will be compared to the observational data, including the color-magnitude diagrams of dwarfs spheroidals, obtained by the HST. ------------------------------------------------------------------------------ Prop. Type: AR Category: AGN/QUASARS ID: 10284 Cycle: 13 Title: Formation of Structure in AGN Accretion Disk Winds: Theory and Observational Implications PI: Isaac Shlosman HST observations of UV emission- and absorption-line spectra in AGN indicate the presence of highly structured outflows, characterized by complex large-scale flow patterns and small-scale clumpiness. These outflows are best explained as winds coming off accretion disks around supermassive black holes, propelled and shaped by a combination of line-radiation pressure and hydromagnetic forces. We propose to make the first comprehensive study of hybrid radiative/hydromagnetic winds in the context of AGN flows. We will particularly focus on a new class of instabilties, "radiative-magnetoacoustic'' modes, that show great promise for explaining both the global properties of the winds {velocity fields, mass loss rates} as well as the small-scale clumpiness. Our results will be fed into a 3D radiative transfer code to compute synthetic BEL and BAL line profiles, to study their time and shape variability, that can be directly compared with existing {and future} HST observations of AGN. ------------------------------------------------------------------------------ Prop. Type: AR Category: HOT STARS ID: 10285 Cycle: 13 Title: Accreting White Dwarfs and Neutron Stars Near the Galactic Center PI: Mark Morris We propose to analyze NICMOS observations of the central 5 pc of the Milky Way Galaxy in order to identify the nature of X-ray sources recently detected in a deep set of Chandra observations. We plan to determine the relative numbers of high-mass X-ray binaries with characteristic ages of 10^7 years, and magnetically accreting cataclysmic variables with ages of over 10^9 years. The results will provide information about the recent star formation history, the propensity for binaries to form, and the mass of stellar remnants at the Galactic center. ------------------------------------------------------------------------------ Prop. Type: GO Category: ISM AND CIRCUMSTELLAR MATTER ID: 10286 Cycle: 13 Title: Probing the Dynamics and Shock Physics of the Cas A Supernova Remnant PI: Robert Fesen Cassiopeia A {Cas A; SN 1680} is the youngest known and closest example of an oxygen-rich, core-collapse supernova remnant. A two-year WFPC2 survey of part of the remnant yielded many new insights including realization of the stunning amount of fine-scale detail present in the ejecta, and the first precise location of the reverse shock front in the main shell via rapid emission and structural changes visible over 2 yrs. In addition, these data revealed over 100 new ejecta knots located out ahead of the forward blast wave in a small region where only a handful were known from ground-based images. We propose a follow-up survey program aimed at obtaining hi-res images of the entire remnant in the ejecta's four major emission lines. A separate set of ACS and NIC3 [Si VI] images of the NW reverse shock filaments will be taken 3-4 months following the main Cycle 12 survey images. These will allow us to the trace individual ejecta knot deceleration dynamics, excitation, and evolution during reverse shock passage. Analysis of the emission line fluxes will make use of custom shock models generated by us for Cas A. These data will also provide data on outer knot chemistry and expansion asymmetries particularly in regard to the collimation of the NE and SW jets of O, Si, Ca-rich ejecta. A major aim of this program is to acquire a superb two-year image database covering the entire remnant to allow a detailed shock physics and dynamics study. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10287 Cycle: 13 Title: Stars in Extended HI Disk Galaxies PI: Holland Ford Half of gas rich galaxies have HI disks extending well beyond their optical extents. This gas is a significant potential fuel repository for future star formation. How can galaxies can store such quantities of ISM without any apparent star formation? These extended gas disks have well maintained velocity dispersions and dynamical structure. What is keeping them warm? Perhaps there is star formation, but at such low levels it is not readily apparent. We have begun investigating this problem by looking for low-level star formation in extended HI disk galaxies. Our first target was the spectacularly dark matter dominated galaxy NGC2915. In this case our hypothesis was proven to be correct. We found indications for low level star formation in two ways. {1} Our ACS WFC images show a noticeable blue plume of stars in the g vs g-V as well as the V vs V-I color magnitude diagrams. The blues stars extend over the full area of the WFC and are highly clumped. {2} Previous deep Halpha images shows a few very faint HII regions near the Holmberg radius. The weakness of the HII regions and the large numbers of blue {B} stars suggests that the IMF is truncated at the upper end compared to typical IMF parameterizations. This could imply that H-alpha surveys underestimate the true star formation rate. Another surprising result of the ACS observations is that the old population also extends well passed the Holmberg radius and includes globular clusters. We propose to observe a second galaxy for this program - NGC4789A {DDO154}. Like NGC2915, it also has HI extending more than five times the Holmberg radius in a fairly well ordered disk. In this case the old stellar population is comparetively weak, and the foreground reddening is much less. This second set of observations will give us a check on the generality of the NGC2915 results. In particular an IMF that does not extend up to O star formation could have major implications for metal production, kinetic energy release and ionization of the intergalactic medium. ------------------------------------------------------------------------------ Prop. Type: AR Category: QUASAR ABSORPTION LINES/IGM ID: 10288 Cycle: 13 Title: The astrophysics of the intergalactic medium at intermediate redshifts PI: David Kirkman We will use the 334 low resolution FOS spectra and the 31 STIS spectra already in the archive to determine the properties of the 0.3 < z < 2 IGM. All of the mentioned spectra are of bright QSOs and cover part of the Lyman alpha forest. We will compute traditional line statistics, but more importantly we will compute a number of pixel statistics using the same analysis methods used by groups that simulate the Lyman alpha forest. Examples of the pixel statistics include the flux power spectrum, the distribution of flux per pixel, and the mean flux decrement of the Lyman alpha forest. The results will enable for the first time a detailed comparison between data and theory at z < 1.7. Specific scientific issues that will be addressed with the results of this research include {1} The spatial structure of the IGM, {2} The thermo-dynamical state of the IGM, {3} The intensity and evolution of the UV background, and {4} The effects of galaxy feedback on the IGM. ------------------------------------------------------------------------------ Prop. Type: AR Category: ISM ID: 10289 Cycle: 13 Title: The Astrophysics of Heterogeneous {Clumpy} Stellar Outflows PI: Adam Frank HST imaging has revealed many circumstellar environments to consist of highly inhomogeneous media. The presence of such "clumpy" mass distributions will have significant consequences for large-scale flows such as mass loss from young and evolved stars as well as strong shocks propagating through interstellar clouds. While clumping can cause dramatic changes in the properties of such flows there remains a fundemental gap between the relatively few theoretical studies of large scale clumpy flow systems and observational interpretations. In this proposal we outline a theoretical study of clumpy flows in circumstellar outflows using a new, advanced adaptive mesh refinement numerical code known as AstroBEAR. This tool is being developed to handle multi-physics astronomical phenomena {situations in which many physical processes such as magnetic fields, ionization, chemistry, and radiation transport must be simultaneously simulated}. Our study will provide unparalleled resolution to study the radiative gasdynamic, magneto-gasdynamic and photo-ionization evolution of heterogeneous flows. The code will track ionization and micro-physical states in the flow allowing detailed comparison with HST observations of YSO jets and Planetary Nebulae. We plan to apply the code to the observations of clumpy bow shocks and internal working surfaces in HH 1-2, HH34, and HH46/47. We will also conduct studies relevent to the stellar wind blown bubble PNe systems NGC 2392 and NGC 6751. ------------------------------------------------------------------------------ Prop. Type: GTO/FOS Category: ID: 1029 Cycle: 0 Title: SPECTROPOLARIMETRY OF QSOS, BLAZARS AND AGN -- CYCLE 0 PI: Roger Angel Measurement of the spectrum of polarization has proven to be a powerful tool in deciphering emission processes and source geometry in AGN. This program will extend these observations into the UV below 3000A. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10290 Cycle: 13 Title: Constraints on galaxy formation models from size evolution of galactic disks and spheroids PI: Rachel Somerville The radial sizes of disks and spheroids are fundamental properties of galaxies, and must be connected with the efficiency of star formation, yet neither numerical nor semi-analytic galaxy formation models are currently able to model them accurately. We propose to compile measurements of disk and spheroid sizes from the Sloan Digital Sky Survey {SDSS}, Great Observatories Origins Deep Survey {GOODS}, and GEMS {Galaxy Evolution from Morphology and SED} survey to characterize in a single consistent analysis the evolution of galaxy sizes from z=5 to the present. We will confront these observations with predictions from three different paradigms of galaxy evolution: {1} a no-evolution model {2} a backwards-evolution model and {3} a hierarchical model based on semi-analytic techniques. For {3}, we will develop new physically motivated modeling of the sizes of disks and spheroids, which has not previously been done self-consistently in a semi-analytic model set within the complete framework of the Cold Dark Matter merging hierarchy. We will account for the formidable selection and measurement biases and cosmic variance by creating synthetic images based on each model paradigm, and running the actual object detection and structural fitting software on these images to create mock catalogs of "observed" galaxy properties. We will use Bayesian methods to quantify the parts of parameter space that are favored within each paradigm, and to assess which model paradigm is favored overall by the data. By carrying out this program, we hope to gain insight into the physical origin of observed galaxy sizes and fundamental scaling relations and their evolution through cosmic history. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10291 Cycle: 13 Title: The Distribution of Stars Around the Massive Black Hole at the Galactic Center PI: Farhad Yusef-Zadeh We believe that the Galactic center provides the best opportunity for investigating the distribution of stars and gas in the immediate vicinity of a supermassive black hole, at a level of detail that will not be accessible in any other galactic nucleus. We propose to utilize approximately 150 HST NICMOS archival images to investigate the nature of the surface brightness distribution within the inner few tens of arcseconds of the Galactic center. In particular, we will examine the claim that there is a deficiency of stars within the inner 1 arcsecond of Sgr A*. This could be evidence of the core radius of the nuclear stellar distribution or it might be due to the depletion of late-type stars with high mass-to-light ratios. Yet another possibility is ejection of stars from the central 1 arcsecond by a past or present binary black hole. ------------------------------------------------------------------------------ Prop. Type: AR Category: STELLAR POPULATIONS ID: 10292 Cycle: 13 Title: Theoretical Studies of the Cores of Globular Clusters PI: Gordon Drukier HST observations of globular cluster cores have resulted in many radial-velocity and proper-motion data sets, with the potential for many more. These have led to various claims for the existence of intermediate-mass black holes in some globular clusters. The theoretical underpinning of these claims is very weak, however. We propose to produce new models of globular cluster cores, both with and without black holes, in order to redress this lack and allow us to make the most effective use of the HST data. ------------------------------------------------------------------------------ Prop. Type: AR Category: COSMOLOGY ID: 10293 Cycle: 13 Title: The Assembly History of Disks and Bulges out to z=1 PI: Richard Ellis We propose to exploit the unique set of ACS multi-color images in the Northern GOODS field in conjunction with a new ground-based database of infrared photometry and high quality Keck spectroscopy. The overall goal is to correlate the dynamical and photometric properties of disks and bulges in the context of popular models for galaxy assembly. The resolved colors and physical scales of bulges in the redshift range 0.3100 z=1 disks will be analyzed with extended rotation curves to address the important question of whether stellar disks were mature and established at early epochs. The program represents a concerted attempt to address the origin of key components which form the basis of the Hubble sequence of galaxies. ------------------------------------------------------------------------------ Prop. Type: AR Category: ISM ID: 10294 Cycle: 13 Title: The SN 1987A/LMC Deep Field PI: Stephen Lawrence We propose to astrometrically register and co-add the complete archive of WFPC2 PC-chip imaging centered on SN 1987A, creating a "SN 1987A Deep Field." These data span 16 epochs between 1994 Feb and 2002 May in six broad-, one medium- and three narrow-band filters with total exposure times ranging from 1.3--11.4 hours. This dataset will be used to: 1} map out the faintest line-emitting structures in the photoionized bipolar circumstellar nebula surrounding SN 1987A, 2} generate fading lightcurves and [OIII]/{H-alpha+[NII]} line emission maps of the various component substructures of this nebula, 3} establish a highly-accurate astrometric grid of stars within 20 arcseconds of SN 1987A, 4} generate very deep {m~25.5--26.5} broad-band photometry of these same LMC field stars, and 5} identify any variable stellar sources in the field. Additionally, we would seek to register and stack the surrounding WF chip images, extending the stellar and ISM field out to 2 arcminute radius. Once we have accomplished our goals we will make these images publically available. Further science that would be available from these publicly-released deep field images includes: 1} a deep map of LMC interstellar line emission unrelated to SN 1987A, which can be correlated with other imaging and spectroscopic datasets, 2} a small, but deeper, set of stellar photometry than currently exists in this field from which stellar population, IMF and extinction studies can be done, and 3} a sample of variable stars and other stellar types potentially useful as distance estimators. ------------------------------------------------------------------------------ Prop. Type: AR Category: SOLAR SYSTEM ID: 10295 Cycle: 13 Title: The Escape of Oxygen from Mars PI: Jody Wilson This proposal is to perform detailed analysis of STIS observations of the upper atmosphere of Mars, using an ionospheric model, general circulation model results for the neutral atmosphere, and various recent spacecraft observations of Mars. The end goal is to better understand the escape of oxygen, and by extension water, from Mars. The observations have yielded limb profiles of atomic hydrogen, atomic oxygen, and carbon monoxide with 24 km vertical resolution and a field of view that is thousands of km long. Most of the hydrogen and some of the oxygen atoms thus detected are escaping from Mars. There are no other measurements of volatiles escaping from Mars with nearly such high spatial resolution and large field of view. The data analysis in the original observing proposal will derive spatially-averaged escape rates of hydrogen and possibly oxygen at the time of the observations. This archival research will go beyond that analysis by investigating how the escaping species diffused through the upper atmosphere to reach the exobase and relating these observations of current escape rate to the time history of escape. The escape of water from Mars has had a major impact on its climate history, the understanding of which is a major scientific goal of NASA's Office of Space Science. ------------------------------------------------------------------------------ Prop. Type: AR Category: AGN/QUASARS ID: 10296 Cycle: 13 Title: Searching for Quasar-Intrinsic Absorption Through Time Variability PI: Rajib Ganguly We propose to use multi-epoch, low-resolution spectra of quasars from the HST archive to look for narrow absorption lines that exhibit time variability. This is an economical test for identifying absorbers that are intrinsic to the quasar central engine, and also provides constraints on the density an/or location of the gas. Narrow absorption lines {NALs} which appear in the spectra of quasars are very powerful tool to diagnose the physical conditions {e.g., ionization, geometry} from a variety of structures, ranging from the ISM of the Galaxy, to the central engine of the quasar. The primary signatures that distinguish intrinsic NALs from intervening NALs are partial coverage of the background source and time variability. The former requires high spectral resolution which can be observationally expensive. We have completed a pilot study using associated NALs {those which appear near the quasar redshift} and have devised an approach to efficiently select time-variable absorption using multi-epoch spectra from different instruments. We wish to expand our search to the ~100 quasars that have archived multi-epoch low-resolution spectra. The quasars span a large range of redshifts and luminosity, and the proposed study will allow us to select low- and high-velocity intrinsic NALs. Furthermore, we can decipher the underlying cause of the variability - bulk motion of the gas, or ionization changes - which have differing observational signatures. ------------------------------------------------------------------------------ Prop. Type: AR Category: STELLAR POPULATIONS ID: 10297 Cycle: 13 Title: The Local Environments of Supernovae PI: Schuyler Van Dyk The locations of supernovae {SNe} in the local stellar and gaseous environment in galaxies, as measured in high spatial resolution WFPC2 and ACS images, contain important clues to their progenitor stars. They provide accurate determinations of any association of SNe with H II regions or star clusters. In cases where multi-filter observations are available, we can determine the local stellar population, setting constraints on the mass of the progenitor, we can also search for possible attenuation of the SN by dust in the host galaxy by studying the colors of the stars in its environment. By checking the fields for background sources, we can correct the existing SN light curves and luminosities if necessary. When a SN has been observed incidentally, information can be gained on its optical and UV emission. Deep HST images can be used to find light echoes of SNe, as well as recover SNe interacting with circumstellar material at very late times. A direct search for the progenitor stars of SNe can be made in pre-existing HST images of their locations; as the number of archival HST images steadily increases, along with the number of newly discovered SNe, positive identifications become progressively more likely. In Cycle 13, we plan to extend our successful work from previous cycles. A major improvement is that very good ground-based coordinates are now available for numerous recent SNe. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10298 Cycle: 13 Title: Structural Evolution of Galaxies with GOODS and the Ultra-Deep Field PI: Seth Cohen We propose to study the evolution of the internal structure of galaxies for z<2. We will use existing ACS archival data from the two GOODS fields, along with the Hubble Ultra-Deep Field {UDF}. We will take maximal advantage of image depth and resolution, and use all four BVi'z' bands along with the wealth of available spectroscopic and photometric redshifts in these fields. We propose to: {1} Utilize our U-band database of over 300 nearby galaxies of all types and inclinations to calibrate quantitative structural measurements of these ACS images of galaxies with z<2 and take advantage of the multiband aspect of the Archival ACS data. {2} Apply a fully two dimensional Fourier Decomposition technique to quantify the existence of structural features {types of spiral features and bars or lack thereof} as a function of redshift to trace to formation of the present day Hubble sequence. {3} Use the deeper UDF images to study the reliability of such measurements over the wider GOODS fields and to push these measurements to fainter flux levels only where it can be justified using what is learned in {1}. {4} Produce and distribute a catalog of our results. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10299 Cycle: 13 Title: Morphological analysis of z=5.7 Lyman Alpha sources in the GOODS/UDF fields PI: Norbert Pirzkal We propose to carefully measure the morphology of z=5.7, narrow band selected Lyman Alpha emitters in the GOODS-S and UDF fields. The candidate objects will be selected using existing observations of these fields taken from the ground, under sub arcsecond seeing conditions, and using two narrow band filters {823 nm and 815nm}. While the number of detections of high redshift Lyman Alpha sources has been steadily increasing in the past year, very little is known about the source of the Lyman Alpha emission. The observed high Lyman Alpha equivalent widths of these objects have been explained using a variety of scenarios such as extreme youth of the stellar population, zero metallicity objects, energetic winds or type II quasars. Studying the morphology of these objects should provide us with a unique opportunity to differentiate between several processes believed to be behind the observed Lyman Alpha emission. Recently, and soon to be made, public HST ACS observations of the GOODS/UDF fields, with their high angular resolutions and its well calibrated, stable PSF provide us with a unique opportunity to study the clumpiness and spatial extension of these objects. ------------------------------------------------------------------------------ Prop. Type: AR Category: COSMOLOGY ID: 10300 Cycle: 13 Title: Properties of moderate-redshift galaxy groups associated with gravitational lenses PI: Christopher Fassnacht Strong evidence indicates that the primary lensing galaxies in many gravitational lens systems are associated with compact groups. We are taking advantage of this association to conduct an active ground-based program to find galaxy groups at moderate redshifts. Because the lens galaxies are typically in the redshift range of 0.3 1 in the COSMOS Field PI: Lin Yan We propose to identify the population of extremely red galaxies {EROs} in the COSMOS treasury dataset, by combining the primary F814W images with their NICMOS F160W parallels. COSMOS parallels with NICMOS provide an unprecedented combination of extraordinary depth {Vega=24}, area coverage {200 sq. arcmin} and spatial resolution. The ERO selection will be limited by the F814W depth, so the entire red galaxy sample will consist of high significance detections suitable for quantative morphological analysis. We will measure the surface density of red galaxies {I-H > 3} fainter than current ground-based surveys can detect in order to determine whether the counts flatten beyond H=20.5. We will establish whether the large disk fraction {60%} seen in the optical holds true in near-infrared morphologies. And we will determine whether ERO clustering strength has any morphological dependence. ------------------------------------------------------------------------------ Prop. Type: AR Category: ISM ID: 10304 Cycle: 13 Title: Departures from Axisymmetry in Planetary Nebulae PI: Matthew Bobrowsky It is well known that outflows from planetary and proto-planetary nebulae often exhibit axial symmetry. What is less well known are the *departures* from axial symmetry, which need to be investigated if we are to have a complete understanding of how planetary nebulae form and evolve. A study of the departures is very timely, as 3D hydrodynamic numerical simulations are now being developed. The HST archive contains ~3000 exposures of >400 different galactic planetary or proto-planetary nebulae. By measuring the departures from axisymmetry for these targets, we will learn how the departures are related to, and caused by, the physical and dynamical conditions of the nebulae and central stars. We will produce a catalog for the community that includes classifications and comparisons of the departures, and correlations with physical and dynamical properties. We will apply our results to departures from axisymmetry observed in PNe and in other types of objects, e.g., SN 1987A, Eta Carinae. We have measured asymmetries for a few sample objects; so we know we will obtain reliable, quantitative results that we {and others} will use to understand the origin of the departures from axisymmetry in a variety of objects. Long after our work on this project ends, the catalog of PN parameters will continue to benefit the wider community. ------------------------------------------------------------------------------ Prop. Type: AR Category: AGN/QUASARS ID: 10305 Cycle: 13 Title: Outflows from Seyfert galaxies: a challenge to current models PI: Daniel Proga We propose to continue our study of outflows from active galactic nuclei {AGN}. This phenomenon has been extensively observed with HST as well as modeled. The overall result from previous studies, including our own ongoing HST program, is that broad absorption lines {BAL} in QSOs can be well understood and reproduced within the framework of radiation-driven disk wind models. It is also very likely that the same model is capable of explaining broad emission lines. However, this model is less successful in explaining narrow absorption lines {NAL} observed in Seyfert galaxies. Therefore, we propose to extend the model by including magnetic field effects. Hydromagnetic propulsion is a likely mechanism responsible for producing low velocity outflows from larger radii and thus explaining NAL and their lack of short-term variability. We will continue to use the multi-dimensional, time-dependent, magnetohydrodynamical code ZEUS to compute the wind structure. We will also compute synthetic line profiles and continuum spectra based on the theoretical model and compare the results with HST/STIS and other observations. In general, we propose to follow the procedure which we successfully applied to winds in cataclysmic variables and BAL QSOs. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10306 Cycle: 13 Title: Archival Study of Merger-Induced Populations in Early-Type Galaxy Cores PI: Jodie Martin Hierarchical formation models predict that early-type galaxies are built up over an extended period from mergers of smaller systems, a process which should leave long-lived signatures in their light profiles and stellar population colors. Merger events should have continued up to relatively recent times {the last 1-5 Gyr}, and many ellipticals and S0 bulges should therefore show evidence of multiple, discrete, intermediate-age populations. Although there is substantial observational support for a dissipational merger origin for some early-type galaxies, most do not exhibit the expected anomalies in either their light profiles or color distributions. However, existing searches have primarily been monochromatic and those which used multi-bands studied only narrowly defined subsamples of early-type galaxies. Here we propose an archival study of high resolution, broad-band, multi-color images of the cores of a large sample of 167 early-type galaxies which are representative of the general population. This is the most extensive search intended to probe spatially-segregated, multiple population components with ages in the range 1-5 Gyr. Our sample consists of early-type galaxies in a wide range of environments from the field to groups to rich clusters. There is very little information on the color structure of core stellar populations of early-type galaxies in different environments and how they may relate to gaseous merger histories and our program would effectively explore new terrain. Simulations of mergers show that gas generally falls deep into the potential well to scales within a few 100 pc of the center before forming stars. An effective search for distinct populations must therefore be able to resolve these scales, which is possible for a meaningfully large sample only with HST. ------------------------------------------------------------------------------ Prop. Type: AR Category: STELLAR POPULATIONS ID: 10307 Cycle: 13 Title: Photo- and Spectro-Chemical Evolution Models for Starburst Galaxies PI: Gerardo Vazquez We propose to develop new chemically consistent evolutionary synthesis models for young stellar populations containing massive stars, including Wolf-Rayet stars. Such populations are the powering sources of starburst galaxies at low and high redshift and are major chemical pollutants of the interstellar and intergalactic medium. The new models are based on the successful Starburst99 code, which will be expanded to allow for stellar evolution at arbitrary {not discrete} chemical composition, including metallicity zero. We will supplement our current grid of stellar models by newly developed evolutionary tracks with rotation. The chemical evolution models will not make the instantaneous recycling approximation and will account for infall and outflows. Existing chemical evolution models do either have to rely on these assumptions or, if they do not, their adopted stellar models make them inapplicable to young massive populations. ------------------------------------------------------------------------------ Prop. Type: AR Category: COSMOLOGY ID: 10308 Cycle: 13 Title: SLACR: The Simulation Lyman Alpha Comparison Repository PI: Romeel Dave I propose to establish SLACR, the Simulation Lyman Alpha Comparison Repository. SLACR is a publically-accessible full-service website containing the data and software tools necessary to generate and analyze artificial Lyman alpha forest spectra drawn from state-of-the-art cosmological hydrodynamic simulations. These artificial spectra can be analyzed alongside ultraviolet quasar and AGN spectra taken using e.g. HST/STIS, in order to {1} Test current theories of the IGM; {2} Constrain the physical state of absorbing gas seen in quasar spectra; {3} Assess biases and uncertainties due to sample incompleteness, continuum fitting, and Voigt profile fitting; {4} Constrain physical and cosmological parameters of the IGM from absorption line data; and {5} Study the relationship between IGM absorbers and large-scale structure as traced by galaxies. SLACR will be an invaluable model comparison and data interpretation tool for HST observers studying the Lyman alpha forest, associated metal absorption systems, "missing baryons" and the warm-hot intergalactic medium, and galaxy-absorber correlations. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10309 Cycle: 13 Title: The Globular Cluster Systems of Low Mass Spiral Galaxies PI: Anil Seth We propose to study the globular cluster systems of approximately twenty edge-on, low mass, late type spiral galaxies using archival ACS snapshot data. This sample of galaxies falls in a range of masses and morphologies neglected by previous studies. Analysis of this sample will enable us to study variations in globular cluster system properties and their correlation with galaxy mass and morphology. Specifically, we will be able to address the correlation of metal-rich clusters with bulge mass, the possible increase of specific frequencies at lower galaxy masses and the galaxy mass dependence of globular cluster destruction mechanisms. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10310 Cycle: 13 Title: Windows of the Early Universe beyond Redshift 7 PI: Wei Zheng Deep ACS images such as UDF are our most powerful probe of the early universe to date, with the discovery of many z~6 candidates. Thousands archival ACS images have covered areas whose sum is significantly larger than the GOODS fields, providing an ideal opportunity to further search for objects at z>7, characterized as z-band "dropouts." We will carry out a systematic search of these objects by combining multi-band ACS images, with deep ground-based infrared photometry. Our goals are: {1} Discovery of {bright} z>7 galaxies, to probe the reionization epoch of the intergalactic medium; {2} Study of the luminosity function of galaxies at z>6. The results will provide insight into the z>10 universe, particularly the bright end of the source distribution, which is crucial for the JWST. ------------------------------------------------------------------------------ Prop. Type: AR Category: GALAXIES ID: 10311 Cycle: 13 Title: The Physical Nature of Galaxy Morphology During the Peak Epoch of Galaxy Formation PI: Charles Steidel We propose to use the deep ACS images obtained by the Great Observatories Origins Deep Survey {GOODS} in combination with a sample of ~300 spectroscopically identified galaxies with 1.46} or if this formation was delayed up to z~1-2 by the intense UV-radiation field present at higher redshifts. The depth and high spatial resolution of the UDF are required in order to detect the low-surface-brightness stellar population associated with the galaxy halo and to separate and spatially resolve it from the central, high-surface-brightness component. ------------------------------------------------------------------------------ Prop. Type: AR Category: SOLAR SYSTEM ID: 10322 Cycle: 13 Title: Electron Impact Simulations of Io's Atmosphere PI: Laurence Trafton August 1999 HST/STIS observations of Io in Jupiter's shadow by Bagenal et al. {Program 8169} revealed 1700-5000 A emission from SO2, SO, and S I that was attributed to impact excitation/dissociation by plasma torus thermal electrons. The conclusions of their analysis were limited by their simplified model of Io, necessitated by the lack of laboratory data and information on the complex geometry of Io's patchy atmosphere and volcanoes. Since then, many Galileo observations of Io have been published which make a detailed model atmosphere for this epoch possible with few free parameters. In addition, laboratory experiments have better-defined both the electron-impact and NUV absorption cross-sections of SO2. Meanwhile, we have developed the capability to simulate the emission from the interaction of plasma particles with Io's neutral atmosphere, overlaying a radiation code onto our 3-D Monte Carlo flow field model of Io without making any of the unrealistic approximations of the original analysis {i.e., uniform isothermal atmosphere; no energy lost by the exciting electrons; and no absorption by SO2}. We propose to use these spectral images to constrain the remaining free parameters of this simulation to yield column abundances and atmospheric electron densities on the Jupiter-facing side of Io. The atmospheric S/SO2 abundance ratio is a diagnostic of SO2 dissociation in the internal volcanic magma that would constrain the volcanic process. These eclipse observations are unique; and they constrain models of Io's molecular atmosphere in ways no other extant data can. ------------------------------------------------------------------------------ Prop. Type: AR Category: STELLAR POPULATIONS ID: 10323 Cycle: 13 Title: ORIGIN OF THE GLOBULAR CLUSTER FUNDAMENTAL PLANE PI: Dean McLaughlin HST has provided many revolutionary new insights on the existence, formation and properties of star clusters in the Universe. One of the most important findings has been that star formation in almost any environment involves the formation of massive stellar clusters which look very much like what is expected of halo globular clusters when they were young. This discovery has rejuvenated ideas about globular cluster formation and star formation in general. Nonetheless, our understanding of the globular cluster formation process remains woefully incomplete. Although the integrated properties of globular clusters in external galaxies have long been studied from the ground, only with Hubble has it become possible to resolve the interiors of individual clusters in the halo of M31 and more distant galaxies. This has shown that globular clusters always have the same typical half-light radius of about 3 pc. This generalizes earlier findings for Milky Way clusters to a wide range of galactic environments and metallicities. Even more, with Hubble it is becoming increasingly clear that the same is true for young massive clusters. Phrased differently, the properties of clusters of all types define a remarkably uniform fundamental plane. While the ubiquity of this plane becomes clearer with every new Hubble observation, it remains a mystery what processes during cluster formation regulate its existence. It is also not understood why clusters {size independent of mass} and galaxies {size increases with mass} follow such different scaling relations. We will target these questions with a theoretical study of cluster formation. Using a semi-analytical approach we will study which processes and parameters are the driving force behind the observed relations. Theoretical work is badly needed to provide a coherent framework for the interpretation of the many important cluster results that Hubble has provided. Our study is therefore ideally suited for the Hubble Theory Program. ------------------------------------------------------------------------------ Prop. Type: AR Category: COSMOLOGY ID: 10324 Cycle: 13 Title: The Morphology of Ly-alpha Emission Galaxies at z=3.11 in the GOODS-S Field PI: Caryl Gronwall The discovery of large numbers of Lyman-break galaxies has revolutionized our ability to study the distant universe. Today, narrow-band surveys have finally caught up and are detecting Ly-alpha emission-line galaxies {ELGs} from z=2.4 to z=6.5. These are important objects: not only do they sample a part of the galaxy luminosity function that is inaccessible to the Lyman-break technique, but they also tend to be younger and less chemically evolved. As a result, these ELGs present us with a unique opportunity to study galaxies in the process of formation. We have performed several ground-based narrow-band surveys for ELGs at z~3.1, including one centered on the Chandra Deep Field South. Spectroscopy has confirmed that our objects have broad {~450 km/s}, asymmetric line profiles, consistent with that of a starburst galaxy. We propose to use archival HST ACS WFC observations of the Chandra Deep Field South from the GOODS treasury program to study the morphology of Ly-alpha ELGs at z=3.11. Our recent ground-based survey of this field contains about 10 Ly-alpha ELGs within the GOODS ACS WFC pointings. The F775W and F850LP images will detect the objects' rest-frame UV continuum, and allow us to measure their structure on sub-kpc scales. With these data we can probe the physical nature of these distant objects and derive important new insights on the nature of galaxy formation. In addition, we will directly compare the properties of our ELGs to similar objects found at higher redshift {4 < z < 7}, and to the Lyman-break galaxies contained in the field. This sample is an important lower redshift counterpart to recent discoveries of Ly-alpha ELGs at higher redshift {z = 4 - 7}. In addition, we will be able to directly compare the properties of the emission-line sources to Lyman-break galaxies at the same redshift in the same field discovered by the GOODS team. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10325 Cycle: 13 Title: Low Redshift Cluster Gravitational Lensing Survey PI: Holland Ford This proposal has two main scientific goals: to determine the dark matter distribution of massive galaxy clusters, and to observe the high redshift universe using these clusters as powerful cosmic telescopes. Deep, g, r, i, z imaging of a sample of low-z {0.2-0.4} clusters will yield a large sample of lensed background galaxies with reliable photometric redshifts. By combining strong and weak lensing constraints with the photometric redshift information it will be possible to precisely measure the cluster dark matter distribution with an unprecedented combination of high spatial resolution and area coverage, avoiding many of the uncertainties which plague ground-based studies and yielding definitive answers about the structure of massive dark matter haloes. In addition, the cosmological parameters can be constrained in a largely model independent way using the multiply lensed objects due to the dependence of the Einsteinng radius on the distance to the source. We can also expect to detect several highly magnified dropout galaxies behind the clusters in the redshift ranges 4-5 5-6 and 7-8, corresponding to a drop in the flux in the g, r, and i bands relative to longer wavelength. We will obtain the best information to date on the giant arcs already known in these clusters, making possible detailed, pixel-by-pixel studies of their star formation rate, dust distribution and structural components, including spiral arms, out to a redshift of around z~2.5 in several passbands. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10326 Cycle: 13 Title: The Morphological, Photometric, and Spectroscopic Properties of Intermediate Redshift Cluster Galaxies PI: Holland Ford We will use the ACS/WFC to image 8 fields in the outskirts of the kT=5.8keV, X-ray cluster RX J0152-13 at z=0.83, for which we obtained imaging in four central fields during Cycle 11. The resulting wide-field mosaic of RX J0152-13 will enable direct study of the population of galaxies falling into this cluster and will provide a much needed comparison to our on-going wide-field study of the more massive, 10.5keV cluster MS1054-03 at the same redshift. Imaging RX J0152-13 to twice its viral radius enables us to: {1} trace the transformation of infalling field spirals into cluster early-types using, e.g., the morphology-density relation to large radii and very low local densities; {2} determine the importance of galaxy-galaxy interactions, i.e., whether the frequency of such encounters in the infall region is as unexpectedly high as found in MS1054-03; and {3} study in detail the star-formation histories of the most recently accreted members via accurate colors and morphologies. A comparison of RX J0152-13 with MS1054-03 will also allow us to directly probe the dependence of galaxy evolution on cluster mass. Only by pairing the wide-field ACS mosaic of RX J0152-13 with multi-object spectroscopy from the Magellan, Keck, and VLT telescopes can we test predictions from galaxy formation models, understand how field spirals evolve into early-type cluster members, and better constrain the formation of galaxies in general. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10327 Cycle: 13 Title: ACS Imaging of a High-Redshift Cluster of Galaxies PI: Holland Ford This programme uses ACS observations of the high-redshift radio galaxy MRC1138-262 {z=2.16} to investigate massive galaxy and cluster formation in the early Universe. This field is unique in that it is known to contain overdensities in both line-emitting {both Lyman-alpha and H-alpha} and continuum {4000A break} objects. Utilizing the excellent angular-resolution and field-coverage of HST/ACS we can obtain the colors and morphologies for a substantial fraction of these protocluster galaxies. These morphologies and colors will be compared to studies of field galaxies at similar redshifts {e.g., from GOODS}. In addition, very deep images of the radio galaxy itself, the presumed central dominant galaxy of this cluster, will allow us to study in detail the process of formation for the most massive known galaxies. The properties of continuum and Ly-alpha clumps within the radio galaxy will be compared in relation to the radio structures. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10328 Cycle: 13 Title: Massive Black Holes in Early Type Galaxies PI: Holland Ford This program is a continuation of the Cycles 11 and 12 ACS/GTO programs 9293 and 9986. Recently, a nearly perfect relation has been recognized between the masses of the black holes {for 3x10^6 Msun < M_BH < 3x10^9 Msun} at the centers of galaxies and the velocity dispersions of their bulges. However, uncertainties over the exact slope of the correlation still remain, and it is not known if such a relation extends to black holes of lower and higher masses. The discovery of small {r ~ a few hundred pc}, well defined, dust and gas disks in the nuclei of some active elliptical galaxies opened a new avenue for measuring central mass distributions. When ionized gas is present, a small number of high spatial resolution {e.g. STIS} spectra are sufficient to characterize the disk dynamics and the galaxy's central mass {e.g., M87, M81, NGC 4374}. We propose to use STIS spectroscopy to measure black hole masses, using gas dynamics, in the centers of several brightest cluster galaxies {BCGs}, 2 nearby galaxies with low velocity dispersions, and a number of early-type galaxies known to harbor small nuclear dust disks. The proposed targets encompass a wide range of black hole masses, allowing us to fully examine the M_BH - sigma relationship. In Cycle 11, we obtained H-alpha and continuum images of most of the targets to fully characterize their gaseous and dust morphologies as well as their core stellar surface profile. In Cycle 12, we completed the imaging {NGC 7720} and performed STIS spectroscopy of two of the best candidates, NGC 404 and NGC 2768. In this Cycle 13 program, we continue the STIS spectroscopy for two other galaxies, NGC 6166 and NGC 7720. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10329 Cycle: 13 Title: Coronographic Search for Planets arround Nearby Stars PI: Holland Ford We will use the HRC coronagraph to search for planets, disks, and exo-zodiacal dust around nearby stars. We have selected the following stars: alpha Cen A and B, tau Ceti, and epsilon Eridani. The observations of each star will be taken at two or more epochs. The observations will be broken into a sequence of short exposures and taken at different roll angles to compensate for "telescope breathing" during the orbit. As a further precaution, the observations will be scheduled after the closest possible nearby pointing in order to minimize thermal changes in the OTA during the first orbit of observations. After matching phases, the PSFs from one star will be subtracted from the other star. ------------------------------------------------------------------------------ Prop. Type: GTO/FOS Category: ID: 1033 Cycle: 0 Title: SEARCH FOR MISDIRECTED BL LAC OBJECTS -- CYCLE 0 PI: Roger Angel FOC images will be obtained in the UV and visible of galaxies whose isotropic properties are the same as those of BL Lac objects. A search will be made for weak unresolved UV nuclei that would be expected if the relativistic beaming theory of normal BL Lac emission is correct. Candidate nuclei found this way will be studied with the FOS. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10330 Cycle: 13 Title: Coronagraphic search for disks around nearby stars PI: Holland Ford We will use the coronagraphic and imaging modes of the High Resolution camera to study of the role of circumstellar disks in planetary system formation over timescales of ~1-1000 Myr. Our targets comprise pre Main-Sequence {MS} and MS stars, selected by infrared excess, and targets selected from SIRTF surveys. Some targets, like Beta Pictoris have debris disks that have been detected at optical or near-IR wavelengths, while others have disks inferred from mid-IR or ISO observations. We will obtain multicolor images of each target's circumstellar environment for the purpose of {1} detecting and characterizing disk morphologies over all scales {including warps and regions of enhanced or depleted density}, and {2} seeking evidence of embedded planets. Direct and occulted images will be recorded for studying the disks within 2 arcseconds of these targets; the coronagraph will be used to image the outer regions of the disks. Together with existing infrared observations, we will provide constraints on the sizes, distribution, and composition of dust grains. Unconfirmed disks will first be imaged in F606W, and if they exist we may later observe them in F435W and F814W. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10331 Cycle: 13 Title: Jovian Satellites PI: Holland Ford The icy Galilean satellites form an integral but poorly understood component of Jupiter's magnetospheric system. While the Pioneer and Voyager spacecraft encounters yielded evidence for the existence of a source of oxygen ions beyond Io's orbit, conclusive evidence that Europa and Ganymede possess thin oxygen atmospheres was only recently provided by HST/GHRS detections of faint far-UV airglow emissions of OI. Moreover, the OI emission on Ganymede is localized to the region of the satellite's poles, consistent with an auroral excitation source that would be expected from the internal magnetic field of Ganymede. More recently, spectrally resolved images of Ganymede obtained with STIS have confirmed this result and demonstrated the variation in location and brightness of the OI emissions with the position of Ganymede relative to Jupiter's plasmasheet. The energy and source of the exciting electrons remain unknown and there is little or no relevant in situ Galileo data that bear directly on this question and thus the determination of the molecular abundance remains highly uncertain. However, the energy can be constrained by the observation of the forbidden OI red line at 6300 Ang, but this requires observation when the satellite is in Jupiter's shadow, to avoid the emissions being swamped by the strong solar reflected light. Europa similarly shows the UV OI emissions, and recent HST/STIS observations show a complex time-dependent variation in the spatial distribution of these emissions. Europa does not have an intrinsic magnetic field, but rather the Jovian field at Europa is modified by a magnetic field induced by Europa's rotation. We will investigate Kivelson's suggested European conducting ocean by timing observations to coincide with different orientations of the induced magnetic field. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10332 Cycle: 13 Title: Starburst Galaxies and Their Population of Super Star Clusters PI: Holland Ford Starbursts are ideally suited to study the evolution of high mass stars, the physics of star formation, and the chemical enrichment of the intergalactic medium {IGM}. Starbursts efficiently form Super Star Clusters {SSC} which may be young protoglobular clusters. High resolution imaging will address two important outstanding issues: 1} how long starbursts last and 2} whether SSCs are indeed young globular clusters. The duration of starbursts is important because: {1} it determines how efficiently a starburst can heat and enrich the IGM; {2} the duration combined with estimates of the fraction of galaxies which host starbursts yields the total number of starbursts a galaxy can suffer. Finally, since local starbursts are analogs to high-z galaxies, the results have implications on the initial formation timescale of galaxies. Starburst duration will be determined from HRC imaging of two face-on starburst galaxies rich in SSCs. The UV to optical colors of the SSCs, which represent single burst chronometers, will yield their reddening and ages. The range of ages gives the starburst duration. The nature of SSCs will be investigated by imaging four of the nearest starbursts in three bands. By comparing the sizes of their SSCs at different wavelengths we will address the issue of whether SSCs suffer from early mass segregation. Without some mass segregation the velocity dispersions of SSCs suggest that they are deficient in low mass stars, and hence may not represent true proto-globular clusters. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10333 Cycle: 13 Title: Comet Hale-Bopp at large heliocentric distance PI: Holland Ford The objective is to determine the size, shape, and possible presence of a small, possibly bound, companion. The latter has been reported by Marchis et al. using the ADONIS adaptive optics system on the ESO 3.6 meter telescope. They claim separations of the two components of 0.23'' {November 1997} and 0.36'' {January 1998} when the comet was 3.3 and 4.1 AU from the Sun. Such a companion is not evident in any STIS images recorded by Weaver et al., but these were single snapshots in time and the companion may have been occulted. The discovery of a bound companion, and the subsequent determination of its orbital period, would provide the first determination of a cometary mass and the density of a cometary nucleus. At large heliocentric distances there will still be residual dust coma so the highest possible spatial resolution {HRC near 300 nm} is needed to model the coma and photometrically isolate the nucleus. The near infrared is best suited for evaluation of the spatial distribution of the dust coma. With proper choice of filter it is also possible to search for a gas coma {CN at 388 nm}. Ideally the comet should be imaged over a complete 11.3 hour rotation period, but a half period would be sufficient to obtain an idea of the shape of the reflecting body. Hale-Bopp is visible throughout 2002. During the period 1 March 2002 to 28 February 2003 the heliocentric distance increases from 15.2 to 17.3 AU. The expected nucleus magnitude {visible} is 16.5-17.0 ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10334 Cycle: 13 Title: i-Band Dropouts around High-z Radio Quasars PI: Holland Ford We will carry out deep ACS/WFC imaging of three high-redshift radio quasars to search for an excess of dropouts. Also see program 9291 and 9777. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10335 Cycle: 13 Title: Black Holes in Globular Clusters PI: Holland Ford Search for >3000 solar mass black holes at the centers of three Galactic globular clusters using stellar proper motions. ------------------------------------------------------------------------------ Prop. Type: CAL/OTA Category: ID: 10336 Cycle: 12 Title: 2-Gyro Reacquisition Test PI: Thomas Brown This proposal will test the software that will be used to perform target reacquisition when HST only has two working gyroscopes. ------------------------------------------------------------------------------ Prop. Type: GO/PAR Category: COSMOLOGY ID: 10337 Cycle: 13 Title: The COSMOS 2-Degree ACS Survey NICMOS Parallels PI: Nicholas Scoville The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a companion to program 10092. ------------------------------------------------------------------------------ Prop. Type: GTO/ACS Category: ID: 10338 Cycle: 13 Title: NICMOS Imaging of a z=2.2 Protocluster: The Color-Magnitude Relation at High-Redshift PI: Holland Ford To establish the epoch when galaxy environment manifests itself as a large-scale evolutionary process, we propose to extend the study of galaxy colors and morphologies to a protocluster at z=2.16. Here the universe is only 3 Gyrs old and significant differences are expected between scenarios favoring a morphology-radius relation over a morphology-density relation. In addition, because the fractional age differences among cluster galaxies are larger, study of the color-magnitude relation provides considerable leverage for determining the epoch of early-type galaxy formation. To facilitate direct comparison to studies at lower redshift, one must probe the same rest-frame wavelengths with high photometric accuracy and at similar physical scales. Its near-infrared photometric stability {low, constant background} and ability to image large areas of sky at high angular-resolution {compared to adaptive optics} makes HST/NICMOS ideal for this program. Four pointings of NICMOS camera 3 will result in rest-frame optical, high resolution images of 13 confirmed protocluster members, and an additional 25 candidate protocluster members including 26 EROs. These galaxies were selected with a variety of techniques and span a range of projected radii within the protocluster. The proposed observations constitute a unique opportunity to extend the study of galaxies in overdense regions to an early time in cosmic history. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10339 Cycle: 13 Title: PANS PI: Adam Riess Type Ia supernovae {SNe Ia} provide the only direct evidence for an accelerating universe, an extraordinary result that needs the most rigorous test. The case for cosmic acceleration rests on the observation that SNe Ia at z = 0.5 are about 0.25 mag fainter than they would be in a universe without acceleration. A powerful and straightforward way to assess the reliability of the SN Ia measurement and the conceptual framework of its interpretation is to look for cosmic deceleration at z > 1. This would be a clear signature of a mixed dark-matter and dark-energy universe. Systematic errors in the SNe Ia result attributed to grey dust or cosmic evolution of the SN Ia peak luminosity would not show this change of sign. We have obtained a toehold on this putative ``epoch of deceleration'' with SN 1997ff at z = 1.7, and 3 more at z > 1 from our Cycle 11 program, all found and followed by HST. However, this is too important a test to rest on just a few objects, anyone of which could be subject to a lensed line-of-sight or misidentification. Here we propose to extend our measurement with observations of twelve SNe Ia in the range 1.0 < z < 1.5 or 6 such SNe Ia and 1 ultradistant SN Ia at z = 2, that will be discovered as a byproduct from proposed Treasury and DD programs. These objects will provide a much firmer foundation for a conclusion that touches on important questions of fundamental physics. ------------------------------------------------------------------------------ Prop. Type: GTO/FOS Category: ID: 1034 Cycle: 0 Title: M87'S JET, NUCLEUS, AND HOT CORONA (FOS NO. 12): CYCLE 0 OBSERVATIONS PI: Holland Ford WF/PC narrow band images of M87 will be used to isolate emission line regions near the nucleus and jet. FOS spectra of these clouds will be used to i) map the velocity field near the nucleus, ii) understand physical conditions and ionization mechanisms in these clouds, and iii) measure chemical composition of the clouds. FOS spectra of the stellar nucleus and synchotron knots in the jet will be used to establish long-base-line spectral indices and to look for spectral features. Long exposure ultraviolet spectra of the nucleus and jet will be used to look for absorption lines from M87's hot corona. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10340 Cycle: 13 Title: PANS PI: Adam Riess Type Ia supernovae {SNe Ia} provide the only direct evidence for an accelerating universe, an extraordinary result that needs the most rigorous test. The case for cosmic acceleration rests on the observation that SNe Ia at z = 0.5 are about 0.25 mag fainter than they would be in a universe without acceleration. A powerful and straightforward way to assess the reliability of the SN Ia measurement and the conceptual framework of its interpretation is to look for cosmic deceleration at z > 1. This would be a clear signature of a mixed dark-matter and dark-energy universe. Systematic errors in the SNe Ia result attributed to grey dust or cosmic evolution of the SN Ia peak luminosity would not show this change of sign. We have obtained a toehold on this putative ``epoch of deceleration'' with SN 1997ff at z = 1.7, and 3 more at z > 1 from our Cycle 11 program, all found and followed by HST. However, this is too important a test to rest on just a few objects, anyone of which could be subject to a lensed line-of-sight or misidentification. Here we propose to extend our measurement with observations of twelve SNe Ia in the range 1.0 < z < 1.5 or 6 such SNe Ia and 1 ultradistant SN Ia at z = 2, that will be discovered as a byproduct from proposed Treasury and DD programs. These objects will provide a much firmer foundation for a conclusion that touches on important questions of fundamental physics. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10341 Cycle: 12 Title: The D/H Ratio in C/2002 T7 {LINEAR} PI: Harold Weaver Measuring the D/H ratio in comets is one of the most important scientific objectives in planetary science. A comparison of the D/H ratio in comets to the value measured in the Earth's oceans can be used to assess whether cometary impacts contributed significantly to the delivery of water and other volatiles to the Earth. A comparison of the cometary ratio with the value in other solar system reservoirs {e.g., in the solar wind and the atmospheres of the Giant Planets}, and to values observed in the interstellar medium, can be used to determine how primitive cometary matter is. Our recent detection of the deuterium Lyman-alpha line in C/2001 Q4 {NEAT} demonstrates that HST has a new and potentially important role to play in this exciting area of research. Fortuitously, another moderately bright comet, C/2002 T7 {LINEAR}, is well-placed for HST observations in early June, and we request 8 orbits of HST time to measure deuterium in this comet. If our observations are successful, the number of comets for which D/H has been measured will be nearly doubled. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: GALAXIES ID: 10342 Cycle: 12 Title: Hubble Heritage Observations of NGC 1300 PI: Keith Noll Observing NGC1300 in four bands for Hubble Heritage project. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10343 Cycle: 13 Title: X-ray from misaligned FRI jets: IC/CMB emission from a fast spine? PI: Rita Sambruna There is evidence that FRI jets have a fast "spine", consisting of relativistically moving plasma, and a slow "wall", decelerated by entrainement of ambient gas. This opens the interesting possibility that inverse Compton scattering of the CMB photons {IC/CMB} off the relativistic electrons could contribute to the high-energy emission from the fast spine. This strongly beamed radiation is visibile only in closely aligned FRI jets, i.e., acccording to unification schemes, in BL Lac objects. Thus, we propose to observe 2 radio-selected BL Lacs with prominent radio jets to search for IC/CMB X-ray emission and confirm unification models. This study will impact models for the origin of the FRI/II division. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10344 Cycle: 13 Title: Sensitive X-ray surveys of nearby globular clusters NGC 6544, NGC 6838 {m71}, and NGC 6656 {M22} PI: Ronald Elsner We propose moderately deep ACIS-S surveys of the nearby globular clusters NGC 6544, NGC 6838 {m71}, and NGC 6656 {M22}. We request two orbits of HST/ACS time to study the crowded core of NGC 6544. Existing archival HST and ground-based optical data suffice for M22 and M71. These observations will provide high-sensitivity surveys of the quiescent low-mass x-ray binary, cataclysmic variable, milli-second pulsar, and chromospherically active binary populations of these clusters, important inputs to models of globular cluster evolution. We will detect the newly discovered milli-second pulsars in NGC 6544 and M71 if they are as bright as the faint milli-second pulsars in 47-Tuc. We will confirm or exclude the identification of an apparent dwarf nova with an x-ray source in the core of M22. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10345 Cycle: 13 Title: Coordinated Multiwavelength Obsevations of AE Aqr PI: Christopher Mauche We propose to conduct an ambitious campaign of coordinated multiwavelength observations of the former supersoft X-ray binary and current magnetic propeller AE Aqr. Recent XMM observations have thrown into doubt the source of the X-ray emission and the heating of the optical and UV emission line regions. We propose to observe AE Aqr for 2 binary orbits with the Chandra HETG to measure the radial velocity variations of the X-ray emission lines and constrain the plasma density. We also propose to obtain 6 orbits of HST high-resolution time-tagged UV spectroscopy and 12 hrs of VLA time, to which we will add mm through gamma-ray data. These data will provide the most complete picture of the locations, mass motions, energetics, and interrelationships of the various emission regions. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10346 Cycle: 13 Title: Coronal Flaring and the Neupert Effect on the Active Binary Sigma Gem PI: Alexander Brown We propose coordinated HETGS, STIS, and radio {VLA, VLBA, MERLIN, Arecibo} observations of the RS CVn binary Sigma Gem to observe flaring and quiescent coronal emission, test whether the flares show the Neupert effect expected from chomospheric evaporation models, and determine the flare energy budget. HETGS will measure changes in the coronal emission measure, temperature, density, and elemental abundances. Radio continuum emission will provide a proxy for the high energy particles accelerated during magnetic reconnection. STIS Fe XXI spectra will measure the flare dynamical energy losses. Sigma Gem is an ideal target because it is one of the brightest RS CVns in X-rays, single-lined, and flares 40% of the time. Its long duration flares increase the likelihood of tracking flare evolution. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10347 Cycle: 13 Title: Resolving the Puzzle of Hybrid Star Coronal X-rays PI: Thomas Ayres We propose 20 ks HRC-I pointings to detect 3 memebers of the so-called "hybrid star" class, and 50 ks to confirm a previous HRC-I detection of the archetype noncoronal giant Arcturus. Coronal activity, mirrored in X-ray emission, is important to the Sun-Earth connection, the fate of primitive planetary atmospheres, and a broad reaching set of magnetic phenomena in diverse cosmic environments. Our program will explore the limits of X-ray activity across the "coronal dividing line, " focussing on targets for which ROSAT-era detections have been challenged recently. Assessing the true levels of coronal activity in these objects has important implications for understanding the initiation of choromospheric winds in red giants, a key phenomenon whose origins remain elusive. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10348 Cycle: 13 Title: The Production of X-ray Emission in Classical T Tauri Stars PI: Gregory Herczeg We propose to obtain a 150 ks HETG spectrum of the Classical T Tauri Star {CTTS} V4046 Sgr. The unknown source of strong X-ray emission remains a glaring weakness in our understanding of energetics around young stars. An HETG observation of the CTTS TW Hya suggested that the physical properties of the hot gas around accreting stars may be different from solar-like coronae. This difference hints that accretion may produce most of the X-rays from CTTSs. However, this tentative conclusion is based on observations of only one CTTS, that may not be representative of its class. We seek to verify this conclusion, and to obtain a better understanding of the temperature, electron density, and abundances of hot gas around CTTSs, by obtaining a high S/N HETG spectrum of an X-ray bright CTTS. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10349 Cycle: 13 Title: A Uniform Study of Globular Cluster X-ray Sources: the Keys to Cluster Dynamical Evolution PI: Walter Lewin We propose to extend our ongoing studies of the dynamical evolution of globular clusters by observing their populations of low-luminosity X-ray sources. Many of these sources are binary systems {or have evolved from them} and hold the key to the cluster's dynamical evolution. We propose observations of a variety of clusters with widely different physical properties such as central concentration, cluster size and mass, which are all key ingredients in the formation and evolution of binaries. To make this study as uniform as possible, the clusters will be observed to the same limiting luminosity. Joint observations with HST will allow for definitive source identification. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10350 Cycle: 13 Title: X-ray Binaries in the Ultrahigh Collision Rate Globular Cluster NGC 6388 PI: Haldan Cohn We propose a joint Chandra-HST study of the massive, high density globular cluster NGC 6388 to study its large expected populations of quiescent low-mass X-ray binaries {qLMXBs} and bright cataclysmic variables {CVs}, and to test for the presence of an intermediate-mass black hole {IMBH}. NGC 6388 has the highest predicted X-ray binary production rate of any Galactic cluster. The qLMXBs will be used to constrain neutron star accretion models, and neutron star masses and radii. The CVs will be used to investigate the effects of cluster structure, metallicity, initial binary fraction, and dynamical history on accreting binary populations. The proposed 3 orbits of HST U-band imaging would complement deep HST V and I-band imaging, already in-hand, for identifying Chandra sources. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10351 Cycle: 13 Title: X-ray em ission from fast moving shocks in theprotostellar jet HH 154: a binding diagnostic of the emission medium PI: Fabio Favata We propose to measure the proper motions in the X-ray source associtasted with the HH 154 jet.This is the only known protostellar jet, where the X-ray enmission can be studied in detail. Our numericval simulations show that the X-ray source is produced in a fast-moving post-shock region {500 km/s}, and earlier HST observations {1996, 1998} together with ground based spectra identifythe potential region from which the X-rays should emanate. Detection {or lack of} the X-rays with Chandra, and the associated optical region with HST will either strongly confirm {or falsify} our model. This will constitute the basis for a general theory for the formation of X-rays in protostellar jets. Understanding and modellling the emission mechanism of X-rays is key to estimate the lifetime and evolution of the X-ray jets and understand their influence on the star {and planetary-} formation process in general. Associating the right optical material {HST} with the X-ray source {Chandra} provides both proper motions {and true speeds}, as well as {by observing in H-alpha and [SII]} determining the {post-} shock properties in the recombination region. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10352 Cycle: 13 Title: A Study of the Physics of Extended Relativistic X-ray Jets, Discovered in our Chandra Survey PI: Herman Marshall We will measure the changing flow speeds, magnetic fields, and energy fluxes in well-resolved quasar jets found in our short-exposure Chandra survey by combining new, deep Chandra data with radio and optical imaging. We will image each jet with sufficient sensitivity to estimate beaming factors and magnetic fields in several distinct regions, and so map the variations in these parameters down the jets. HST observations will help diagnose the role of synchrotron emission in the overall SED, and may reveal condensations on scales less than 0.1 arcsec. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10353 Cycle: 13 Title: Galactic Bulge Chandra-HST Survey PI: Jonathan Grindlay We propose a deep survey for low-luminosity accretion-powered sources {CVs, qLMXBs and wind-fed pulsars} that likely constitute the underlying populations in the cusp of sources around SgrA*. A 100 ksec pointing at l, b = 0.10, -1.43 degr. allows the survey closest to the galactic center that can still be reached in the optical. With 12 orbits of HST, we can complement the two outer fields {Baade's Window and Stanek's Window} obtained with Chandra-HST to complete the most sensitive X-ray/optical survey of the Galactic Bulge. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10354 Cycle: 13 Title: Probing the Link between Galactic Bars & Starburst/AGN Activity in NGC1672/NGC7771 PI: Leigh Jenkins Multi-wavelength data have shown that a substantial fraction of barred spiral galaxies exhibit enhanced star formation activity in their central regions. This phenomena is however poorly studied at X-ray energies. We propose joint Chandra/HST observations of two barred starburst galaxies NGC1672 and NGC7771. We request Chandra observations to spatially resolve the X-ray emission into point sources and diffuse emission, enabling us to trace the star formation on small spatial scales and search for obscured starburst/AGN activity. We also request a complimentary optical imaging program with HST/ACS, permitting us to identify the optical counterparts to X-ray point sources and map the optical emission from star formation in their local environments on similar scales to Chandra. ------------------------------------------------------------------------------ Prop. Type: GO Category: ID: 10355 Cycle: 13 Title: Planet-Induced Activity enhancements in the HD 179949 Systems PI: Steven Saar Many exoplanets are gas giants extremely close {<0.1 AU} to their parent stars, suggesting the posssiblitiy of exotic interactions. Recently, weakly enhanced Ca II HK emission was found in the HD 179949 system, phased to the orbital {~3 d} and not to the stellar rotation period {~8 d}. Theory suggests this enhancement is due to a magnetic interaction {MI} between the star and planet. Since the resulting heating should be largest in X-rays, we propose to study the system with Chandra to further characterize the MI. We will use HST to study the MI effect on the planet's ablating atmosphere by observing Doppler shifted H~I around quadrature. These datasets will enable us to test interaction theories, and estimate exoplanetary magnetic fields, mass loss and stellar wind properties. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10356 Cycle: 13 Title: WFPC2 Cycle 13 Decontaminations and Associated Observations PI: John Biretta This proposal is for the monthly WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: SOLAR SYSTEM ID: 10357 Cycle: 13 Title: Saturn's Inner Satellites at True Opposition PI: Anne Verbiscer We request one HST orbit to observe Janus, Epimetheus, Mimas, and Enceladus with WFPC2 exactly at opposition, when the Earth transits the center of the solar disk seen from Saturn on UT 13/14 January 2005. Data obtained at this unique viewing geometry are essential to determining physical properties of the moon's surface, related to its emplacement and evolution, and critical for the interpretation of photometric data obtained by Cassini at higher phase angles. This single observation will be the capstone of 9 years of legacy HST WFPC2 observations of the saturnian system {Cycles 6-12, R. French, PI} from which we have constructed precise, multiwavelength phase curves which demonstrate how the reflectance of these satellites varies with solar phase angle from 0.07 to 6.4 degrees. Each satellite exhibits a dramatic increase in brightness, or "opposition effect", as phase angles decrease below 1 degree. Since 1998 {Cycle 7} the minimum observable phase angle at opposition has decreased each year to 0.07 degrees in Cycle 12; however, the absolute minimum observable phase angle, about 0.02 degrees {limited by the angular size of the Sun viewed from Saturn}, has not been accessible until Cycle 13. Using the same set of broadband filters for continuity with our previous programs, we will place observations made during the Earth transit on the existing UVBRI phase curves and establish the amplitude of each satellite's opposition surge. From these observations we will determine surface properties such as porosity, grain size distribution and particle opacity using radiative transfer models. While the Cassini spacecraft will obtain images at larger phase angles, it will miss entirely the narrow brightness surge near opposition due to orbital constraints. Because these inner satellites will be either lost in or contaminated by the glare of the fully open rings, they are not accessible to ground-based telescopes. The 2005 opposition prese nts the only opportunity for HST to observe the saturnian system during this rare planetary alignment. The next transit of Earth across the solar disk seen from Saturn occurs in 2020; the next central transit occurs in 2049. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10358 Cycle: 13 Title: Guide Star Test for program 10265 PI: Thomas Brown Guide Star Test for program 10265. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10359 Cycle: 13 Title: WFPC2 CYCLE 13 Standard Darks PI: Vera Kozhurina-Platais This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs. ------------------------------------------------------------------------------ Prop. Type: GTO/FOS Category: ID: 1036 Cycle: 0 Title: IMAGING AND SPECTROPHOTOMETRY OF SEYFERT NUCLEI (FOS 14): CYCLE 0 OBSERVATIONS PI: Holland Ford WF/PC narrow band images will be used to isolate clouds near the nucleus and to look for organized structure such as disks, bubbles, and jets. FOS spectrophotometry from 1200A to 7000A will be used to establish density, temperature, chemical composition, ionization mechanisms, and reddening in the emission regions near the nucleus. Line profiles and radial velocities will be used to investigate broadening mechanisms near the nucleus such as turbulence, gas flows, and rotation. Small aperture FOS spectra of the nuclei will be used to separate the broad line region from the narrow line region. The spectra will be used to investigate physical conditions and gas dynamics in the broad line region. Absorption lines in the nuclear spectra will be used to measure the amount and distribution of gas along the line of sight through the parent galaxy. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10360 Cycle: 13 Title: WFPC2 CYCLE 13 INTERNAL MONITOR PI: John Biretta This calibration proposal is the Cycle 13 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays {gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10361 Cycle: 13 Title: Earth Flats PI: Shireen Gonzaga This proposal monitors flatfield stability. This proposal obtains sequences of Earth streak flats to construct high quality flat fields for the WFPC2 filter set. These flat fields will allow mapping of the OTA illumination pattern and will be used in conjuction with previous internal and external flats to generate new pipeline superflats. These Earth flats will complement the Earth flat data obtained during cycles 4-12. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10362 Cycle: 13 Title: WFPC2 Cycle 13 UV Earth Flats PI: Shireen Gonzaga Monitor flat field stability. This proposal obtains sequences of earth streak flats to improve the quality of pipeline flat fields for the WFPC2 UV filter set. These Earth flats will complement the UV earth flat data obtained during cycles 8-12. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10363 Cycle: 13 Title: WFPC2 CYCLE 13 Intflat and Visflat Sweeps and Filter Rotation Anomaly Monitor PI: Shireen Gonzaga Using intflat observations, this WFPC2 proposal is designed to monitor the pixel-to-pixel flatfield response and provide a linearity check. The intflat sequences, to be done once during the year, are similar to those from the Cycle 12 program 10075. The images will provide a backup database in the event of complete failure of the visflat lamp as well as allow monitoring of the gain ratios. The sweep is a complete set of internal flats, cycling through both shutter blades and both gains. The linearity test consists of a series of intflats in F555W, in each gain and each shutter. As in Cycle 12, we plan to continue to take extra visflat, intflat, and earthflat exposures to test the repeatability of filter wheel motions. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10364 Cycle: 13 Title: WFPC2 Cycle 13 CTE Monitor PI: Inge Heyer Monitor CTE changes during Cycle 13. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10365 Cycle: 13 Title: WFPC2 Cycle 13 Photometric Characterization PI: John Biretta Provide a check of the zeropoints and contamination rates in non-standard WFPC2 filters. ------------------------------------------------------------------------------ Prop. Type: CAL/WF2 Category: ID: 10366 Cycle: 13 Title: WFPC2 Cycle 13 Close-Out Photometric Cross-Calibration PI: John Biretta This proposal is to provide additional photometric zeropoint cross-calibration between WFPC2 and ACS photometric filter sets. The proposal consists of observations of T-dwarf 2M0559-14, following similar observations by ACS in program 10056 visit 4. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10367 Cycle: 13 Title: ACS CCDs daily monitor- cycle 13 - part 1 PI: Marco Sirianni This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10368 Cycle: 13 Title: External CTE Monitor PI: Adam Riess Monitor CTE changes during cycle 11. Determine CTE. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10369 Cycle: 13 Title: ACS internal CTE monitor PI: Max Mutchler The charge transfer efficiency {CTE} of the ACS CCD detectors will decline as damage due to on-orbit radiation exposure accumulates. This degradation will be closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs. All the data for this program is acquired using internal targets {lamps} only, so all of the exposures should be taken during Earth occultation time {but not during SAA passages}. This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing {program 8948}, so that results from each epoch can be directly compared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR} data will be obtained over a range of signal levels for both the Wide Field Channel {WFC}, and the High Resolution Channel {HRC}. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10370 Cycle: 13 Title: CCD Hot Pixel Annealing PI: Colin Cox Hot pixel annealing will continue to be performed once every 4 weeks. The CCD TECs will be turned off and heaters will be activated to bring the detector temperatures to about +20C. This state will be held for approximately 12 hours, after which the heaters are turned off, the TECs turned on, and the CCDs returned to normal operating condition. To assess the effectiveness of the annealing, a bias and four dark images will be taken before and after the annealing procedure for both WFC and HRC. The HRC darks are taken in parallel with the WFC darks. The charge transfer efficiency {CTE} of the ACS CCD detectors declines as damage due to on-orbit radiation exposure accumulates. This degradation has been closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs. We will now combine the annealling activity with the charge transfer efficiency monitoring and also merge into the routine dark image collection. To this end, the CTE monitoring exposures have been moved into this proposal . All the data for this program is acquired using internal targets {lamps} only, so all of the exposures should be taken during Earth occultation time {but not during SAA passages}. This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing {program 8948}, so that results from each epoch can be directly compared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR} data will be obtained over a range of signal levels for both the Wide Field Channel {WFC}, and the High Resolution Channel {HRC}. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10371 Cycle: 13 Title: ACS CCD Flash Calibration PI: Colin Cox This activity provides a set of CCD FLASH exposure reference images for each current level/shutter-side/detector combination, for the pair of FLASH LEDs on the instrument side currently in use. It also tests the short-term repeatability at the shortest FLASH exposure times that are expected to be used {1.0 sec}. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10372 Cycle: 13 Title: SBC MAMA Recovery PI: Colin Cox This proposal is designed for the initial turn-on of the ACS MAMA detector and to permit recovery after an anomalous shutdown. Anomalous shutdowns can occur as a result of bright object violations which trigger the Bright Scene Detection or Software Global Monitors. Anomalous shutdowns can also occur as a result of MAMA hardware problems. The Initial MAMA turn-on/recovery from anomalous shutdown consists of three tests: a signal processing electronics check, high voltage ramp-up to an intermediate voltage, and high voltage ramp-up to the full operating voltage. During each of the two high voltage ramp-ups, diagnostics are performed during a dark ACCUM. The turn-on is followed by a MAMA Fold Analysis . The complete sequence is contained in visits 1 through 4. If a second execution is required during cycle 13, visits 5 through 8 will be run and another proposal prepared for possible future occurrences. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10373 Cycle: 13 Title: ACS UV Calibration Monitor and SBC Dark Current PI: Mauro Giavalisco A standard star field {NGC6681} is observed twice during cycle 13, alternating between after and before annealing operations, through all the ACS broad band UV filters. NGC6681 hosts several UV spectro - photometric standard stars for which accurate spectra have been {and will continue to be} measured with STIS. Four SBC dark current exposures taken as the last exposure of each SBC sequence. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10374 Cycle: 13 Title: ACS photometric Stability PI: Mauro Giavalisco This program consists of three parts. In the first part we will observe a subset of the ACS white dwarfs with HRC and ACS to verify repeatability to ~0.2%, because the filter shifts are based on photometric differences between stars of ~1%. These observations are also required to establish relative magnitudes of the primary WD standards at the 0.1% level. Targets should be GD153 and G191B2B, which seems to have the largest V mag error of ~0.008 mag. One orbit on the most important filters, including the grism and the prisms, should be expended with each camera for both stars for a total of 4 orbits. In the second part will observe with HRC and WFC a solar analog star, P330E, to estimate any shifts in the short and the long wavelength cutoffs of selected filters. Complete filter bandpasses can be derived directly from the ratio of grism observations with and without the filter in place. The grism is on filter wheel 1, while four filters of interest F330W, F344N, F660N, and F814W are on wheel 2. Each grism observation requires 3 settings: filter alone, filter+grism, and grism alone. In the third part we obtain high S/N photometric and spectroscopic observations of three red stars, VB-8 {M7}, 2M0038+18 {L3.5} and 2M0559-14 {T5} with HRC and WFC to verify the photometry at the new standard position and to obtain accurate calibration {1% or better} of the grism spectra. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10375 Cycle: 13 Title: Stability of the ACS CCD: Flat fielding, Photometry, Geometry PI: Jennifer Mack This program will verify that the low frequency flat fielding, the photometry, and the geometric distortion are stable in time and across the field of view of the CCD detectors. A moderately crowded stellar field, located ~6' West of the center of the cluster 47 Tuc, is observed every three months with the WFC and HRC using the full suite of broad and narrow band filters. The same field has been observed during SMOV to derive low frequency corrections to the ground flats and to create a master catalogue of positions and magnitudes from dithered observations of the cluster. In Cycles 11-12, this field was observed again using single pointings at various roll angles. The positions and magnitudes of objects are used to monitor local and large scale variations in the plate scale and the sensitivity of the detectors. The Cycle 13 program will continue to monitor these effects and will derive an independent measure of the detector CTE. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10376 Cycle: 13 Title: ACS Internal Flat Field Stability PI: Jennifer Mack The stability of the CCD flat fields will be monitored using the calibration lamps and a sub-sample of the filter set. High signal observations will be used to assess the stability of the pixel-to- pixel flat field structure and to monitor the position of the dust motes. Only internal exposures with the calibration lamps will be required. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10377 Cycle: 13 Title: ACS Earth Flats PI: Jennifer Mack High signal sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the flats currently used by the pipeline and will provide a comparison with flats derived via other techniques: L-flats from stellar observations, sky flats from stacked GO observations, and internal flats using the calibration lamps. Weekly coronographic monitoring is required to assess the changing position of the spots. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10378 Cycle: 13 Title: ACS Polarimetry Calibration PI: John Biretta Observations are made of the Boomerang Nebula {highly polarized reflection nebula} to calibrate the ACS polarizers. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10379 Cycle: 13 Title: Flats Stability PI: Alfred Schultz This calibration proposal is the Cycle 13 NICMOS flat field monitor program. A series of camera 1, 2, & 3 flat fields will be obtained to monitor the health of the cameras. ------------------------------------------------------------------------------ Prop. Type: GTO/FOS Category: ID: 1038 Cycle: 0 Title: IMAGING AND SPECTROPHOTOMETRY OF NUCLEAR ACTIVITY IN LINERS (FOS 15): CYCLE 0 OBSERVATIONS PI: Holland Ford WF/PC narrow band images will be used to isolate ionized gas clouds near the nuclei and to look for organized structure such as disks, bubbles and jets. FOS spectrophotometry from 1200A to 7000A will be used to establish density, temperatures, chemical composition, ionization mechanisms, and reddening in the emission regions near the nucleus. Line profiles and radial velocities will be used to investigate broadening mechanisms such as turbulence, gas flows, and rotation. Small aperture spectra of the nucleus will be used to look for a photoionizing continuum and for line broadening in the nucleus, and will be used to establish physical conditions and dynamics of the nuclear gas. UV absorption lines will be searched for in the nuclear continuum in order to measure the amount and distribution of gas along the line-of-sight through the parent galaxy. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10380 Cycle: 13 Title: Cycle 13 NICMOS dark current, shading profile, and read noise monitoring program PI: Bahram Mobasher The purpose of this proposal is to monitor the dark current, read noise, and shading profile for all three NICMOS detectors throughout the duration of Cycle 13. This proposal is an essentially unchanged continuation of PID 9993 which cover the duration of Cycle 12. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10381 Cycle: 13 Title: Photometric Stability PI: Roelof de Jong This NICMOS calibration proposal carries out photometric monitoring observations during Cycle 13. The format of the program is identical to that of the Cycle 12 program 9995. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10382 Cycle: 13 Title: NICMOS Focus Stability PI: Tommy Wiklind ++++++++++++++++ Visits 11, 12, 21 have not been corrected for missing POS TARG OFFSET {Jan-19-2005} Visit 22, 13, 31, 32, 41, 42 have been corrected {Jan-19-2005} ++++++++++++++++ The purpose of this activity is to determine if the best focus. This program will execute in one month intervals starting about 1 month after the last execution of proposal 9994 {the previous focus monitoring program}. The program starts with a focus sweep using only the NIC1 camera {visit 11}. The following observation is with the NIC2 camera {visit 12} after about 45 days. This pattern is repeated throughout the period except for Feb 15 where also the NIC3 camera is used. In total this will result in 9 orbits. Notice that VISIT #1 #2 refers to visits for #1 sequential visit number for a given camera #2 camera in question visit 32 is therefore the third visit for camera 2. ------------------------------------------------------------------------------ Prop. Type: CAL/NIC Category: ID: 10383 Cycle: 13 Title: NICMOS Cycle 13 Grism Re-Calibration PI: Ralph Bohlin The NICMOS grism is an underutilized resource for science, in particular for precision IR spectrophotometry. This cycle 13 program is a minimal follow up and closeout for the 10 orbit cycle 12 program 9998 and for 14 orbits in 10014. If GO grism usage remains light in cycle 14, this two orbit sensitivity monitoring program could also suffice as a cycle 13 closeout calibration for this mode. The goals of the Cycle 12-13 grism calibration campaign are: 1. Provide a robust characterization of the absolute flux calibration for the two shorter wavelength NICMOS grisms, including quantitative measurement of repeatability and estimates of the uncertainty. 2. Verification to better than 1-percent accuracy of the relative fluxes of the three primary WD standard stars and of the relative fluxes of the three secondary solar analog standard stars to 1.9 microns. The same verification has already been done with STIS {Bohlin, Dickenson, & Calzetti 2001} below 1micron. 3. Characterization of the differences between the WD and the solar analog flux scales in the IR; and establishment of the best basis for all absolute IR flux calibrations, including the other NICMOS filters, SNAP, JWST, and WFPC3. 4. Establishment of one fainter IR standard stars to prove the ability of the NICMOS grism to do precision spectrophotometry at 3-5 magnitudes fainter than the other six standard stars. The fainter standard will provide the basis for relative fluxes on SNAP and may be faint enough for the higher dispersion spectral modes of NIRSpec and MIRI on JWST. SNAP requires standards with ~1-percent relative flux from 0.35-1.7microns to accurately determine the parameters of the equation of state for the dark energy that causes the accelerating expansion of the universe. 5. In summary, these data will establish for the first time an absolute flux basis in the IR that will be of comparable fidelity to the optical flux standards. 6. This cycle 13 proposal will quantify the repeatability of grism observations with a star that has already been observed in cycle 12. CYCLE 12 RESULTS AND CYCLE 13 FOLLOW UP: All cycle 12 data was successfully acquired. One problem is that the repeatability as measured by the comparison of the cycle 11 to the cycle 12 observations of P330E is only +/- 2%, as shown in Fig. 1 {attached to the Phase 1 distribution}. We have extracted and corrected the cycle 12 data for intra-pixel and pixel gap sensitivity variations at each of the 15 dither positions. The rms of these sets of 15 dithered spectra, ie the scatter about the mean of an individual spectrum, is typically 1-2-percent, making the error in the mean <0.5-percent for all the pixels in the central 90-percent of the wavelength coverage.The goal and expectation is for repeatability to better than 1%. The somewhat poorer results may be attributed to flat field differences between the Thompson dither strategy and that used in 9998; or perhaps, there is some synoptic change in the system throughput. In order to distinguish these possibilities and hopefully recover a repeatability of 1%, an observation of one of the cycle 12 standards must be repeated early in cycle 13, using the same dither strategy as 9998. To minimize the measured amount of any synoptic sensitivity change, the observations should be made before the end of 2004. The bulk of the cycle 12 observations were made in the 2004 January through 2004 July time frame, so that the ideal repeatability target was observed early in 2004 and can be observed again this fall. The bright Sloan standard BD+17d4708 is the ideal selection, having been previously observed on 04Jan10. P330E would be a good choice, except that it was previously observed too recently on 04Jun19 to measure any sensitivity change back to 04 Jan; and the scheduling would be rushed to get it before going into solar avoidance in October. ------------------------------------------------------------------------------ Prop. Type: CAL/OTA Category: ID: 10384 Cycle: 13 Title: Focus Monitor PI: Stefano Casertano The focus of HST is measured from WFPC2/PC and ACS/HRC images of stars. Multiple exposures are taken in parallel over an orbit to determine the influence of breathing on the derived mean focus. Observations are taken of clusters with suitable orientations to ensure stars appear in all fields. ------------------------------------------------------------------------------ Prop. Type: CAL/OTA Category: ID: 10385 Cycle: 13 Title: Spectrophotometry of Solar Analog Stars and Nicmos Grism Calibration PI: Ralph Bohlin NICMOS IR Standards {4 orbits} In cycle 12, 24 orbits were used to measure the NICMOS grism mode sensitivities and to establish a set of IR flux standards with a goal of 1% accuracy. However, the G096 setting shows up to 5% peak-to-peak range among the sensitivities derived from the three primary WD standards, as shown in Figure 1 {for the Phase 1 proposal}. The possible causes of this large scatter include changes in the flat field, a systematic change of sensitivity with time, and a fundamental limitation of the repeatability for stars at the WD flux levels. The same residuals for STIS in the 0.8-1.0 micron overlap range are <1%, so that the problem is not with the fluxes for the three primary standard stars. Either there is a systematic trend in the Nicmos grism data that can be removed with more monitoring; or alternatively, repeating the cycle 12 observations should reduce the error in the mean sensitivity by sqrt{2}, if the deviations among the stars are random instrumental fluctuations. The NICMOS cycle 13 calibration program includes 2 orbits to repeat the observations of the bright standard BD+17d4708, which has a very high S/N, so that any change in its response should reflect an instrumental sensitivity difference between cycle 12 and 13. The four Nicmos orbits in this program include one each for GD71 and GD153 in G096 and G141, while two orbits are required for the repeat of G191B2B, where the G206 mode is also included. ------------------------------------------------------------------------------ Prop. Type: CAL/AST Category: ID: 10386 Cycle: 13 Title: Long Term Monitoring of FGS1r in Position Mode PI: Edmund Nelan It is known from our experience with FGS3, and later with FGS1r, that an FGS on orbit experiences long term evolution, presumably due to disorption of water from the instrument's graphite epoxy composits. This manifests principly as a change in the plate scale and secondarily as a change in the geometric distortions. These effects are well modeled by adjustments to the rhoA and kA parameters which are used to transform the star selector servo angles into FGS {x, y} detector space coordinates. By observing the relative positions of selected stars in a standard cluster at a fixed telescope pointing and orientation, the evolution of rhoA and kA can be monitored and calibrated to preserve the astrometric performance of FGS1r. ------------------------------------------------------------------------------ Prop. Type: CAL/AST Category: ID: 10387 Cycle: 13 Title: Monitoring FGS1r's Interferometric Response as a Function of Spectral Color PI: Edmund Nelan This proposal obtains reference point source Transfer Functions {S-Curves} for FGS1r through the F583W filter and the F5ND attenuator at the center position of the FGS1r FOV for a variety of stars of different spectral types. These Transfer Functions are needed to support the analysis of GO science data for the study of close and wide binary star systems and for determining the angular size and shape of extended sources. This proposal observes stars that have been observed in previous cycles to monitor the long term evolution of the FGS1r S-curves. This proposal also {1} monitors the FGS1r Lateral Color response {using stars Latcol-A and Latcol-B}, {2} calibrates the "Pos/Trans" bias of a star's position as determined from Transfer mode and Position mode observations, and {3} calibrates the shift of a star's centroid when observed with F5ND relative to that when observed with F583W. ------------------------------------------------------------------------------ Prop. Type: CAL/STIS Category: ID: 10388 Cycle: 13 Title: SITS biases and darks PI: Linda Dressel For STIS aliveness ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10389 Cycle: 13 Title: ACS CCDs daily monitor - Cycle 13 - Part 2 PI: Marco Sirianni This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10390 Cycle: 13 Title: Serendipitous detection of a debris disk near the Sun PI: Paul Kalas We report the unexpected detection of the Fomalhaut debris disk in scattered light during one orbit of observation for our Cycle 12 program GO9862. This is a major discovery because Fomalhaut is now the closest {7.7 pc} and oldest {~200 Myr} debris disk detected in reflected light. We would like to request Director's Discretionary Time to further study the Fomalhaut disk. The goals are to image the disk around its entire perimeter, increase the signal-to-noise of the detection, and to obtain data at a second wavelength. We will perform a high-resolution study of radial and azimuthal disk asymmetries that are thought to arise from perturbations by planet-mass companions, and we will constrain the physical properties of grain material by obtaining the color of the disk. Because our original Cycle 12 program was designed to study point sources in the field, and the ACS/HRC coronagraph is a limited lifetime resource, it is necessary to acquire these additional data via Director's Discretionary Time during Cycle 13. The observational challenge of high contrast cannot be met by other observatories, and these data will complement new Spitzer results on the Fomalhaut disk at mid and far-infared wavelengths. ------------------------------------------------------------------------------ Prop. Type: CAL/ACS Category: ID: 10391 Cycle: 13 Title: Wavelength and Flux Calibration of the ACS prisms PI: Soren Larsen The wavelength calibration of the SBC {PR110L and PR130L} and HRC {PR200L} prisms will be established by observing a planetary nebula in the LMC and QSOs at carefully selected redshifts. Flux calibrations will be derived for each prism by observing white dwarf standards. ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10392 Cycle: 12 Title: Hubble Heritage Image of the Light Echo around V838 Monocerotis PI: Keith Noll We will obtain a second spectacular color image of the light echo around V838 Mon ------------------------------------------------------------------------------ Prop. Type: GO/DD Category: ID: 10393 Cycle: 12 Title: Hubble Heritage Observations of Eagle Nebula PI: Keith Noll The Hubble Heritage team will use 2 pointings of the ACS WFC to observe Column 5 in M16 as part of a public release image. Filters include broadband: F435W, F555W, F814W along with narrowband: F658N and F502N. ------------------------------------------------------------------------------ Prop. Type: GO Category: GALAXIES ID: 10394 Cycle: 13 Title: Deep imaging of newly discovered globular clusters in the outer halo of M31 PI: Nial Tanvir Globular clusters {GCs} are fossil relics with which we can investigate the processes of galaxy formation and growth. We have recently discovered a sample of GCs, as part of a very wide area CCD survey of M31. These clusters span a range in projected galactocentric distance of 20 - 80 kpc, more than double the radii of the previous most remote known GC. Here we apply for deep ACS images of 13 GCs, which will allow us to study their stellar populations, line-of-sight distances and structural parameters. These will be used to: a} Investigate the merger history of M31, through an examination of variations in the RGB and HB morphologies, particularly to obtain metallicities and check for the presence of any second parameter effect in the HB. d} Determine, in conjuction with ground-based spectroscopy, the dynamical mass of M31 at large radius, providing a direct probe of the mass distribution of its dark halo. ------------------------------------------------------------------------------ Prop. Type: GO Category: COSMOLOGY ID: 10395 Cycle: 13 Title: Environmental drivers of galaxy evolution: an HST survey of dwarf galaxy morphologies in the Abell 901/902 supercluster PI: Meghan Gray Galaxies in dense environments are subject to numerous physical processes that leave a lasting impact, yet studies of galaxy evolution to date have been limited to the most luminous galaxies -- those least sensitive to environmental influence. We propose to explore the environmental drivers of DWARF galaxy evolution: with a mosaic of 9x9 ACS pointings in F606W we will determine morphologies for ~1200 galaxies down to M_V=-14 in the A901/902 supercluster, spanning 3x3 Mpc at z=0.16. The deep ACS data will allow us to probe their surface brightness profiles, shapes, sizes, asymmetry and fine structure such as tidal features. With the addition of extensive existing multi-wavelength data, we will probe the dependence of these important parameters on dark matter content {from weak lensing maps}, the hot intercluster medium {from deep XMM-Newton imaging}, and local galaxy density {from hyper-accurate COMBO-17 photometric redshifts with \delta z=0.02 to m_R=24}, thus disentangling the various environmental processes shaping dwarf galaxy evolution. Furthermore, the 8000+ background galaxies at 0.2