Prop. Type: ENG/STIS/PAR 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: 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: 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: 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: 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/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/PAR 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/PAR 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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 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: 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: 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: 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: 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/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: 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: 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: 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