|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Note: "CalFUSE Version 3: A Data-Reduction Pipeline for the Far Ultraviolet Spectroscopic Explorer" (Dixon et al. 2007) is the definitive documentation for the FUSE data-reduction pipeline. The CalFUSE Pipeline Reference Guide supplements that paper by providing instructions for running the pipeline and detailed descriptions of its calibration files.
Table of Contents
1. Installing the CalFUSE Pipeline1.1 Retrieving the PipelineYou may download the files directly from our FTP site using your browser or transfer them via FTP.
prompt> ftp archive.stsci.edu login: anonymous password: your_email_address ftp> cd pub/fuse/software/calfuse ftp> binary ftp> get INSTALLING_CalFUSEv3.2.3 ftp> get INTRO_TO_CalFUSEv3.2.3 ftp> get cfv3.2.3.sw.tar.gz ftp> get cfv3.2.3.cala.tar.gz ftp> get cfv3.2.3.calg.tar.gz ftp> get cfv3.2.3.calz.tar.gz ftp> quit Uncompress and extract all tarfiles into your calfuse directory. 1.2 Installing the PipelineTo install and compile CalFUSE, please follow the instructions in the file INSTALLING_CalFUSEv3.2.3.1.3 Directory StructureOnce you have installed and compiled CalFUSE, you will have the directory structure shown below.calfuse/v3.2/ bin/ calfiles/ aeff1a100.fit aeff1b100.fit etc. docs/ idl/ include/ lib/ parmfiles/ master_calib_file.dat parm1a015.fit scrn1a015.fit etc. src/ Makefile analysis/ cal/ cfitsio/ fes/ fuv/ libcf/ slalib/ 1.4 Setting Environment VariablesThe CalFUSE pipline uses a number of environment variables to determine the locations of various files:1.4.1 PATHThe environment variable PATH tells the pipeline where to find the executable programs. You should include the directory calfuse/v3.2/bin in your PATH.1.4.2 LD_LIBRARY_PATHThe environment variable LD_LIBRARY_PATH tells the pipeline where to find the dynamically-linked libraries. You should include the directory calfuse/v3.2/lib in LD_LIBRARY_PATH. For Solaris installations, the directory /opt/SUNWspro/lib must also appear in LD_LIBRARY_PATH. On Mac OS X machines, this variable is called DYLD_LIBRARY_PATH.1.4.3 CF_CALDIRThe environment variable CF_CALDIR gives the location of the calibration files required by the CalFUSE pipeline. At the conclusion of the installation procedure described in Section 1.1, this directory will be calfuse/v3.2/calfiles.1.4.4 CF_PARMDIRThe environment variable CF_PARMDIR gives the location of the parameter files required by the CalFUSE pipeline. At the conclusion of the installation procedure described in Section 1.1, this directory will be calfuse/v3.2/parmfiles.1.4.5 CF_IDLDIRThe CalFUSE pipeline uses a couple of IDL routines to generate diagnostic plots in GIF or JPEG format. One produces an image of the detector, operplotted with the extraction windows, and the other the count rate for the LiF and SiC target channels. The environment variable CF_IDLDIR gives the location of the IDL plotting routines. By default, these routines live in calfuse/v3.2/idl, but the user may move them to a different location. If the CF_IDLDIR environment variable is not set, the pipeline does not produce any plots. Note that these IDL routines require the IDL Astronomy User's Library.1.4.6 cfsetup.cshWe have provided a pair of shell scripts called cfsetup.csh and cfsetup.sh to set the environment variables discussed above. Depending which shell you are using, copy either v3.2/bin/cfsetup.csh or v3.2/bin/cfsetup.sh to your home directory and set CF_DIR and CF_VERSION to the appropriate values, e.g.:set CF_DIR="/data1/calfuse" set CF_VERSION="v3.2"Add the following to your .cshrc file (or its equivalent): source cfsetup.csh
2. Running the CalFUSE Pipeline2.1 Overview of the PipelineTo run the code, the command is the same for both TTAG and HIST data:prompt> calfuse P99901010011attagfraw.fit prompt> calfuse P99901010011ahistfraw.fit The following modules are called by the shell script calfuse.csh: cf_ttag_init, cf_hist_init: Converts raw-data file into an intermediate data file (IDF) containing a photon-event list, good-time intervals, and a timeline table. Histogram data are converted to a pseudo-time-tag format. cf_convert_to_farf: Corrects for detector deadtime. Transforms photon coordinates into the Flight Alignment Reference Frame (FARF). cf_screen_photons: Checks data quality. Assigns status flag to each photon. cf_remove_motions: Corrects for mirror, grating, FPA, and spacecraft motions. cf_assign_wavelength: Applies astigmatism and Doppler corrections and assigns a wavelength to each photon. cf_flux_calibrate: Converts WEIGHT to ERG/CM2 for each photon. cf_bad_pixels: Applies image-motion corrections to bad-pixel map. cf_extract_spectra: Extracts LiF and SiC spectra only for target aperture. Wavelength array is user defined; default spacing is 0.013 Å. The pipeline expects to find all data files (*raw.fit, *jitrf.fit, *hskpf.fit) in the current directory. It operates on one detector segment at a time. For each input file, it produces the following output files: an intermediate data file (IDF); a bad-pixel map (BPM) with format similar to the IDF; two extracted spectral files, one for each of the LiF and SiC channels; and (if IDL is installed on your machine) a pair of GIF or JPEG files, one an image of the detector and the other a count-rate plot. For more information, see "CalFUSE Version 3: A Data-Reduction Pipeline for the Far Ultraviolet Spectroscopic Explorer" (Dixon et al. 2007). 2.2 Modifying the Default Parameters2.2.1 Rejecting Daytime PhotonsSay that you are interested only in data obtained during orbital night. Broadly speaking, there are two ways to exclude day-time photons from your data: either modify the screening files before running the pipeline or modify the IDF files afterward. To do the former, simply change the header keyword DAYNIGHT from BOTH to NIGHT in the scrn*.fit files (in the parmfiles directory) and re-run the pipeline. Photons obtained during orbital day will be flagged as bad and excluded from the extracted spectrum.Because CalFUSE does not discard undesirable photon events, but merely flags them, it is possible to change the screening applied to the data without re-running the pipeline. An interactive tool for doing this is the IDL routine cf_edit, but the C program idf_screen provides the same capabilities and runs considerably faster. It is described in FUSE Tools in C. 2.2.2 Extracting Subsets of an ExposureSuppose that you have observed a binary star over several orbits and wish to extract only data obtained during a particular orbital phase. Again, you can either modify the screening parameter files before running the pipeline or modify the IDF files afterward. To do the former, change the good-time interval (GTI) keywords in the screening parameter file (described in Section 3.3.3). Up to 99 user-defined GTIs are allowed. To operate on an IDF file, use the routine idf_cut, described in FUSE Tools in C. Note that you can combine multiple IDFs into a single file, then use idf_cut to pull out all of the data obtained during a particular orbital phase.Now suppose that you want to identify times when the spacecraft was actively tracking a moving target. The housekeeping file contains an array called I_FPD_TRACKING_ON that tells when the Instrument Data System (IDS) is requesting a moving-target motion from the attitude control system. Set your good-time intervals to the times when this flag is 1. It updates once per second. Here's an example: header = headfits('E93818020011attagfraw.fit') expstart = sxpar(header, 'EXPSTART') a = mrdfits('E9381802001hskpf.fit', 1) i= where(a.I_FPD_TRACKING_ON eq 1, n) ; times when tracking is good if (n gt 0) then print, a[i].mjd - expstart 2.2.3 Burst RejectionBurst rejection is performed by the subroutine cf_screen_burst. The program works by rejecting time periods in which the background count rate differs significantly from its median value. These count rates are determined from background regions defined in the BCHR (background characterization) parameter file and stored in the header keywords of the IDF. The use of background regions prevents mistaking variability of the target for bursts and also makes the procedure more sensitive, since the count rate in the background is quite small. We implicitly assume that any burst that affects the observation will also appear in our background regions.The count rate within the integrated background regions is typically 3-15 counts/second, depending on the phase of the orbit and the position of the source (e.g., objects in the CVZ tend to have higher background count rates than those near the equator). To improve counting statistics, the count-rate array is binned by 10-20 seconds. This limits the time resolution for burst removal. For example, if the time sequence is binned by 10 seconds, then the data affected by bursts will be removed in 10-second chunks. Since the background varies with time, it is necessary to determine a reference level against which the time sequence can be compared. To do this, we first determine the median count rate for the entire exposure and mark all points more than three times the median as possible bursts. We then pass the time sequence through a median filter (with a typical averaging time of 10 minutes), disregarding time segments that have been marked as possible bursts. We compare the entire time sequence with this filtered reference and mark all time bins that have a count rate more than 7 standard deviations above the running average. Here we assume Gaussian statistics, so that 1 standard deviation is the square root of the number of counts in that bin. The median filter is then re-calculated, again avoiding bins that have been marked as possible bursts. The procedure is repeated until no new bins are marked. Note: the time interval over which the median filter is determined should be longer than the duration of the bursts. Having established a reference level, we identify as bursts those time segments for which the count rate is 5 standard deviations above the reference level. We consider this to be the minimum detectable event. All photon events that occur during bursts are flagged as bad. While small bursts may dominate weak sources, they will have virtually no effect on bright sources. For this reason, it is possible to specify the minimum count-rate increase required for an event to be removed. By default, this level is set at 5 counts per second, about the average background level; however, for bright sources it could be increased to several hundred counts per second without affecting the spectrum. It is also possible to specify the rejection criterion as a fraction of the integrated source count rate. The characteristics of the burst removal process are controlled by keywords in the screening parameter files (described in Section 3.3.3). In most cases, the default values will provide acceptable results, but there are times when the user may want to make adjustments. The most common are
2.2.4 South Atlantic AnomalyThe South Atlantic Anomaly marks a depression in the Earth's magnetic field that allows particles trapped in the Van Allen belts to reach low altitudes. The high particle flux in this region raises the background count rate of the FUSE detectors to unacceptable levels. The subroutine cf_screen_saa compares the spacecraft's ground track, recorded in the LONGITUDE and LATITUDE arrays of the time-line table, with the limits of the SAA, stored in the calibration file SAAC_CAL as a binary table of latitude-longitude pairs, and flags as bad periods when data were obtained while the spacecraft lay within the SAA. Our SAA model was derived from orbital information and onboard counter data from the first 3 years of the FUSE mission. The size of the SAA contours varies on timescales of weeks, and you may find that a larger coutour is necessary for your data. If so, modify the master_calib_file.dat to read saac005.fit, rather than saac004.fit. Both contours are plotted in this figure.2.2.5 Background SubtractionThe algorithm by which CalFUSE constructs a model background is exhaustively detailed in Dixon et al. (2007). Here are a couple of points not discussed in that article:Sometimes, nebular emission in non-target apertures contaminates the background-sample region but is not bright enough to trigger the bright-background switch in cf_make_ttag_bkgd. To force the program to use this mode, set the keyword BKGDTYPE = -1 in the parameter file scrn*.fit. Both the detector dark count and the scattered-light models will be scaled by the exposure time; no fit will be performed. To change the background sample regions used by cf_scale_bkgd to scale the empirical background spectrum, simply modify the BKG_MIN# and BKG_MAX# keywords in the IDF header. The IDL tool cf_edit, available from the FUSE IDL Tools Reference Page, provides an easy way to do this. For faint emission-line spectra, users may prefer not to subtract the background, but instead fit it as an independent spectral component. To turn off background subtraction, set the keyword RUN_BKGD to NO in the parameter file parm*.fit. 2.3 Combining Data from Multiple ExposuresThe FUSE project has produced a number of tools to combine data from multiple exposures, both IDFs and extracted spectral files. They are discussed in the document FUSE Tools in C.2.4 Detector Distortions in the X DimensionAs described in Dixon et al. (2007), the FUSE wavelength calibration was derived from standard optical expressions and fit to the data with only the constant term (the zero-point of the wavelength scale) as a free parameter. The shifted dispersion solution was used to generate the final wavelength-calibration files, while residuals to the fit were assumed to represent distortions in the detector X scale and incorporated into the pipeline's geometric-correction calibration files.A figure showing these residuals for the X coordinate of the LiF1A LWRS channel appears in the PASP paper. Here are similar plots for all FUSE channels:
The small black dots in these figures are the data points for all apertures and both channels for the given detector segment. They are included in the distortion fit, but weighted 100 times less than the data points for the channel/aperture being fitted. This helps control the fits in wavelength regions where the data are sparce or missing. 2.5 FUSE Effective-Area CurvesThe FUSE flux calibration is discussed in Dixon et al. (2007), which includes a figure showing the time evolution of the effective area of the LiF and SiC channels on detector segment 1A. Here's a plot comparing the December 1999 and May 2006 effective areas for all eight channels:
Effective area of the eight FUSE channels in 1999 and 2006.
3. CalFUSE File Formats3.1 Data FilesFile formats for FUSE raw data, intermediate data, bad-pixel, and extracted spectral files are described in "CalFUSE v3: A Data-Reduction Pipeline for the Far Ultraviolet Spectroscopic Explorer" (Dixon et al. 2007). Header keywords for all of these files are described in the FUSE Data Handbook.3.2 Housekeeping and Jitter FilesOne pair of housekeeping and jitter files is produced for each FUSE exposure and may be retrieved from the MAST archive. They are used by the pipeline to track a variety of spacecraft and instrument parameters, including spacecraft pointing, detector high-voltage level, and various photon count rates. File formats for the FUSE housekeeping and jitter files are described in the FUSE Data Handbook.3.3 Parameter FilesThe files in the calfuse/v3.2/parmfiles directory allow the user to customize the pipeline processing. These files specify the screening to be performed and the calibration files to be used.3.3.1 master_calib_file.datThis file lists each calibration and parameter file that will be used by the pipeline. In general, a separate file is provided for each detector segment. Calibration and parameter files are contained in the directories calfuse/v3.2/calfiles and calfuse/v3.2/parmfiles, respectively. Note the date in the 4th column. For some steps of the pipeline, the optimum calibration file depends on the observation date. FUSE was launched on MJD = 51354.Data format: ASCII file; each record is terminated by a newline. Comment lines are indicated by a # in the first column. Data lines contain 5 columns: calibration keyword, detector segment, filename, modified Julian date, and interpolation method. 3.3.2 PARM_CAL (parm1a015.fit)Keywords in this file give the user (some) control over how the pipeline operates.SPEX_SIC= -1 / SiC extraction window Y center (0-1023) SPEX_LIF= -1 / LiF extraction window Y center (0-1023) EMAX_SIC= 40 / SiC extraction window maximum Y movement EMAX_LIF= 40 / LiF extraction window maximum Y movement Setting SPEX_SIC and SPEX_LIF to -1 directs CalFUSE to determine the best locations for the extraction windows. In this case, the EMAX_SIC and EMAX_LIF keywords specify the maximum amount that the windows may move from their expected positions. To specify the Y position of an extraction window, set the corresponding keyword (SPEX_SIC or SPEX_LIF) to some value in the range 0-1023. You might do this if the pipeline has trouble finding your spectrum, or if you wish to offset the window from your spectrum to obtain a background spectrum (for ttag data only). The following keywords allow the user to skip some of the pipeline-processing steps. RUN_PHAX= 'YES' / PHA X (walk) correction RUN_BRST= 'YES' / Burst rejection RUN_JITR= 'YES' / Jitter correction RUN_ASTG= 'YES' / Astigmatism correction RUN_BKGD= 'YES' / Background subtraction RUN_OPTI= 'YES' / Optimal extractionWhen their keywords are set to 'NO', the walk-correction, burst-rejection, jitter-correction, astigmatism-correction, and background-subtraction steps are not performed. When RUN_OPTI = 'NO', cf_extract_spectra returns a simple, unweighted sum of all good pixels in the extraction window. Bad pixels are not included in the sum. The following keywords control the jitter-screening routine. Times when the tabulated pointing errors exceed the allowed limits are flagged as bad, but only if the tracking flag is greater than or equal to the minimum value. Limits are applied to both the LiF and SiC channels. TRKFLG = 1 / Minimum trustworthy value of TRKFLG DX_MAX = 30 / [arcsec] Allowed pointing error DY_MAX = 30 / [arcsec] Allowed pointing error The following keywords allow the user to specify the wavelength range and bin size of the extracted spectrum. If not set, default values, stored in the wavelength calibration files, are used for each channel. LIF_W0 = / [A] Requested initial wavelength LIF_WMAX= / [A] Requested final wavelength LIF_WPC = / [A] Requested wavelength per channel SIC_W0 = / [A] Requested initial wavelength SIC_WMAX= / [A] Requested final wavelength SIC_WPC = / [A] Requested wavelength per channel
3.3.3 SCRN_CAL (scrn1a015.fit)The keywords in this file control the screening that is performed on a data set.Keyword Default Possible values SAA_SCR ON ON/OFF LIMB_SCR ON ON/OFF DAYNIGHT BOTH BOTH/DAY/NIGHT PHALOW 2 0-31 (integer) PHAHIGH 25 0-31 (integer) BRITLIMB 15. --- (float) DARKLIMB 10. --- (float) NUSERGTI 0 0-99 (integer) GTIBEG01 0. >= 0. (float) GTIEND01 0. >= 0. (float) GTIBEG02 0. >= 0. (float) GTIEND02 0. >= 0. (float) ... MNCNT 5 >= 1 (integer) STDREJ 5 >= 1 (integer) NBIN 15 >= 1 (integer) NSMED 600 >= 1 (integer) SRCFRAC 0.001 >= 0. (float) BKGDTYPE= 1 -1/1 (integer) These keywords are discussed briefly below. SAA_SCR: SAA screening. When ON, cf_screen_saa flags as bad any time intervals during which the satellite passed through the South Atlantic Anomaly. Exposures do not ordinarily extend into the SAA, so turning this step OFF is unlikely to have much effect. LIMB_SCR: Limb screening. When ON, cf_screen_limb_angle flags as bad any time intervals during which the telescope line of sight is closer than BRITLIMB degrees to the sunlit Earth limb or closer than DARKLIMB degrees to the dark Earth limb. Exposures do not ordinarily extend below the specified limb constraints, so the user is unlikely to see any effect from setting this parameter to OFF. The main exception is the case of exposures deliberately obtained of the bright earth for purposes of studying airglow emission. DAYNIGHT: Day/night screening. When set to DAY, only time intervals when the satellite was on the sunlit side of the earth are flagged as good; when set to NIGHT, only time intervals when the satellite was on the dark side of the Earth are set to good; and when set to BOTH, no screening by orbital phase is performed. PHALOW: Minimum acceptable pulse height for ttag data. (No pulse height information is present in HIST mode.) We no longer recommend tightening the pulse-height limits beyond their default values, as a significant number of "real" photon events can be rejected. PHAHIGH: Maximum acceptable pulse height for ttag data. BRITLIMB: The limb angle constraint applied if the Earth limb closest to the telescope boresight is in sunlight. See the discussion for LIMB_SCR above. DARKLIMB: The limb angle constraint applied if the Earth limb closest to the telescope boresight is in shadow. See the discussion for LIMB_SCR above. NUSERGTI: The number of user-defined good-time intervals. These can be used, for example, to extract a particular phase in a binary orbit. All other screening (by SAA, limb angle, day/night, pulse height) is performed as usual. There may be up to 99 user-defined good-time intervals (limited by the 8-character length of FITS keywords). The limits of each good time interval are specified by the time in seconds from the start of the exposure. GTIBEG01: Start of first user-defined good-time interval, specified as time in seconds after the start of the exposure. GTIEND01: End of first user-defined good-time interval, specified as time in seconds after the start of the exposure. GTIBEG02: Start of second user-defined good-time interval, specified as time in seconds after the start of the exposure. GTIEND02: End of second user-defined good-time interval, specified as time in seconds after the start of the exposure. The next five keywords are used by the module cf_screen_burst. They can be adjusted to optimize performance; for details, see Section 2.2.3. MNCNT: Minimum enancement of the background (in counts) needed to flag a burst. Currently = 5. STDREJ: Minimum number of standard deviations from the mean required for a burst to be detected. Currently = 5. NBIN: Size of time bins (in seconds). Ensures that there are a reasonable number of counts in each time step. Currently = 15. NSMED: Time interval (in seconds) used in the median-filter algorithm. Currently = 600. This number is used to determine the background level against which the bursts are measured. It should be longer than the typical burst duration. SRCFRAC: Fraction of the source intensity required for a burst to be removed. For example, SCRFRAC = 0.01 requires that a burst exceed 1% of the integrated source intensity before being removed. Currently = 0.001. BKGDTYPE: For time-tagged data, the background is generally scaled from measurements of unilluminated portions of the detector. If this keyword is set to -1, the background is instead scaled directly from the exposure time and mean intensities of the detector dark count and scattered light. For details, see Dixon et al. (2007). 3.3.4 Background Characterization File (bchr1a003.fit)The background-characterization files contain parameters used to construct the background model. Though considered a parameter file, its data are stored as binary extensions and are not meant to be modified by the user.HDU 1Description: Contains keywords giving history of file. Empty HDU 2Description: Contains a binary table listing the limits of the detector regions used to estimate the background flux. Data format: FITS binary table with 3 columns in a single row. Each entry is an 8-element integer array. The first 6 integers are ymin/ymax pairs for three sample regions. The 7th number is the number of rows in the active aperture region, and the 8th is the total number of active rows on the detector.
HDU 3Description: Lists the detector dark-count rate (in units of 1E-7 counts/s/pixel) as a function of the pulse-height threshold PHALOW, which is set in the SCRN file. Data format: Nine-element array of floating-point numbers in a FITS image extension. intcr=intcrarray[PHALOW]
3.4 Calibration FilesAll calibration files used by CalFUSE are standard FITS format files, except for the FUSE.TLE file, which is in ASCII format. The FITS files generally contain a minimal header, with the actual data being present in extensions. Calibration files that are applied to an entire detector segment (e.g., background, geometric distortions) generally consist of an image the same size as the detector (16384 × 1024 pixels), though some of these files are compressed. Calibration data that are specific to particular spectrograph entrance apertures (e.g., extraction windows, effective areas) are stored in separate extensions of a single file. The filenames shown are the versions distributed with CalFUSE v3.2.3. In all cases for which separate files are used for data from each detector segment, the filename corresponding to detector 1A is used as an example; similar files exist for segments 1B, 2A, and 2B.
AEFF_CAL (aeff1a100.fit)This file contains effective-area curves (in cm2) for each aperture. Because the FUSE sensitivity changes with time, new AEFF_CAL files are calculated every three to six months. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains the effective-area curve the LiF HIRS spectrum. Data format: FITS binary table with 2 columns and 1024 rows. (Data are actually stored as a single row; each table element is an array.)
HDU 3, 4, 5Description: Contains effective-area curves for the LiF MDRS, LWRS, and PINH spectra. Data format: FITS binary table with 2 columns and 1024 rows. HDU 6, 7, 8, 9Description: Contains effective-area curves for the SiC HIRS, MDRS, LWRS, and PINH spectra. Data format: FITS binary table with 2 columns and 1024 rows. AIRG_CAL (airg1a004.fit)This file lists regions of the detector likely to be contaminated by airglow emission.
HDU 1Description: Contains keywords giving history of file. Data format: Empty
HDU 2Description: Contains the positions in detector FARF coordinates of the regions affected by airglow and scattered solar emission lines. These regions are rectangular areas defined by minimum and maximum X and Y pixel values. The table also lists the spectral channel and aperture affected by each region and identifies the atomic species and wavelength of the main contributors included in the areas. Data format: FITS binary table with 8 columns and a variable number of rows. (Data are actually stored as a single row; each table element is an array.)
ASTG_CAL (astg1a011.fit)This file contains corrections for spectral line curvature caused by astigmatism in the Rowland circle grating mount.
HDU 1Description: Contains keywords giving history of file. Data format: Empty
HDU 2Description: Contains the X shift for each pixel in the LiF HIRS spectral image needed to correct line curvature for a point source. Data format: Image 16384 × 150 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. Note: the Y dimension of this image ranges from 133 to 191 pixels, depending on the detector and aperture. To determine the image size, read the keyword NAXIS2 from the header of the desired extension. The zero-point row for the astigmatism correction is stored in the header keyword SLIT_CEN.
HDU 3, 4, 5Description: Contains X shifts for each pixel in the LiF MDRS, LWRS, and PINH spectral images needed to correct line curvature for a point source. Data format: Image 16384 × 165 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords.
HDU 6, 7, 8, 9Description: Contains X shifts for each pixel in the SiC HIRS, MDRS, LWRS, and PINH spectral images needed to correct line curvature for a point source. Data format: Image 16384 × 165 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords.
HDU 10-17Description: Same as HDU 2-9, except for an extended source. Because no astigmatism correction is presently defined for extended sources, these arrays are filled with zeros. Data format: Image 16384 × 165 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. BKGD_CAL (bkgd1a011.fit)This file contains images of the scattered-light component of the detector background for night- and day-time observations. Images are constructed from multiple background exposures totaling hundreds of ksec. Images are binned by 16 pixels in X and normalized to a 1-second exposure. Note that each tabulated value represents the mean of 16 pixels, rather than their total. The pipeline expands the image to the full detector width and scales it to match the scattered light observed in background regions of the detector.
HDU 1Description: Minimal FITS header. Data format: Empty
HDU 2Description: Contains an image of the night-time scattered-light component of the detector background, in units of counts. Data format: Image 1024 × 1024 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. HDU 3Description: Contains an image of the day-time scattered-light component of the detector background, in units of counts. Data format: Image 1024 × 1024 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. CHID_CAL (chid1a014.fit)This file contains the upper and lower limits of the extraction windows. HDU 1Description: Minimal FITS header. Data format: Empty HDU 2Description: Contains the extraction limits for each pixel in the LiF HIRS spectral image, assuming a point source. XPIX is the detector X pixel number; YLOW and YHIGH are the lower and upper boundaries of the extraction window. The header keyword CENTROID contains the mean of the YLOW and YHIGH arrays. Data format: FITS binary table with 4 columns and 16384 rows. (Data are actually stored as a single row; each table element is an array.)
HDU 3, 4, 5Description: Contains extraction limits for each pixel in the LiF MDRS, LWRS, and PINH spectral images, assuming a point source. Data format: FITS binary table with 4 columns and 16384 rows. HDU 6, 7, 8, 9Description: Contains extraction limits for each pixel in the SiC HIRS, MDRS, LWRS, and PINH spectral images for a point source. Data format: FITS binary table with 4 columns and 16384 rows. HDU 10-17Description: Same as HDU 2-9, except for an extended source. Data format: FITS binary table with 4 columns and 16384 rows. DIGI_CAL (digi001.fit)This file lists the expected values of 16 parameters for each detector. The subroutine cf_check_digitizer compares keywords in the data file header with these values and issues a warning message if they are discrepant. HDU 1Description: All data are stored in header keywords: Detector 1 parameters DET1ASCL= 17.0 / DET1 segment A Time (X) image scale factor DET1BSCL= 91.0 / DET1 segment B Time (X) image scale factor DET1AXOF= 183.0 / DET1 segment A Time (X) image position offset DET1BXOF= 107.0 / DET1 segment B Time (X) image position offset DET1AUCT= 227.0 / DET1 TDC-A Upper Charge Threshold setting DET1BUCT= 228.0 / DET1 TDC-B Upper Charge Threshold setting DET1ABWK= 165.0 / DET1 TDC-A Begin CFD Walk setting DET1BBWK= 139.0 / DET1 TDC-B Begin CFD Walk setting DET1AEWK= 165.0 / DET1 TDC-A End CFD Walk setting DET1BEWK= 125.0 / DET1 TDC-B End CFD Walk setting DET1ABSL= 227.0 / DET1 TDC-A Charge Baseline Threshold setting DET1BBSL= 228.0 / DET1 TDC-B Charge Baseline Threshold setting DET1ALCT= 7.0 / DET1 TDC-A Lower Charge Threshold setting DET1BLCT= 7.0 / DET1 TDC-B Lower Charge Threshold setting DET1ALTT= 169.0 / DET1 TDC-A Lower Time Threshold setting DET1BLTT= 143.0 / DET1 TDC-B Lower Time Threshold setting Detector 2 parameters DET2ASCL= 65.0 / DET2 segment A Time (X) image scale factor DET2BSCL= 78.0 / DET2 segment B Time (X) image scale factor DET2AXOF= 107.0 / DET2 segment A Time (X) image position offset DET2BXOF= 80.0 / DET2 segment B Time (X) image position offset DET2AUCT= 227.0 / DET2 TDC-A Upper Charge Threshold setting DET2BUCT= 228.0 / DET2 TDC-B Upper Charge Threshold setting DET2ABWK= 113.0 / DET2 TDC-A Begin CFD Walk setting DET2BBWK= 111.0 / DET2 TDC-B Begin CFD Walk setting DET2AEWK= 114.0 / DET2 TDC-A End CFD Walk setting DET2BEWK= 112.0 / DET2 TDC-B End CFD Walk setting DET2ABSL= 228.0 / DET2 TDC-A Charge Baseline Threshold setting DET2BBSL= 228.0 / DET2 TDC-B Charge Baseline Threshold setting DET2ALCT= 7.0 / DET2 TDC-A Lower Charge Threshold setting DET2BLCT= 7.0 / DET2 TDC-B Lower Charge Threshold setting DET2ALTT= 159.0 / DET2 TDC-A Lower Time Threshold setting DET2BLTT= 149.0 / DET2 TDC-B Lower Time Threshold setting END Data format: Empty ELEC_CAL (elec005.fit)This file contains header keywords describing the detector electronics, including stim-pulse positions and the limits of the active region of each detector. It is read by a number of CalFUSE subroutines. HDU 1Description: All data are stored in header keywords: ACTIVE_L= 512 / Left edge of active area (inclusive) ACTIVE_R= 15871 / Right edge of active area (inclusive) TTAG_BUS= 8000.0 / Maximum IDS count rate in TTAG mode HIST_BUS= 32000.0 / Maximum IDS count rate in HIST mode ABORT_1A= 2.76E-06 / Electronics abort time for 1A CLOCK_1A= 1.50E-06 / Electronics clock time for 1A STATE_1A= 11.68E-06 / Electronics state time for 1A ABORT_1B= 4.66E-06 / Electronics abort time for 1B CLOCK_1B= 1.66E-06 / Electronics clock time for 1B STATE_1B= 10.29E-06 / Electronics state time for 1B ABORT_2A= 5.23E-06 / Electronics abort time for 2A CLOCK_2A= 1.27E-06 / Electronics clock time for 2A STATE_2A= 8.37E-06 / Electronics state time for 2A ABORT_2B= 4.23E-06 / Electronics abort time for 2B CLOCK_2B= 0.0E-06 / Electronics clock time for 2B STATE_2B= 6.31E-06 / Electronics state time for 2B STIMWDTH= 128 / Half width of stim box STIMTOLR= 0.01 / Stim position tolerance STIMLX1A= 236 / Stim 1A left X position STIMLY1A= 805 / Stim 1A left Y position STIMRX1A= 16125 / Stim 1A right X position STIMRY1A= 781 / Stim 1A right Y position STIMLX1B= 262 / Stim 1B left X position STIMLY1B= 757 / Stim 1B left Y position STIMRX1B= 16148 / Stim 1B right X position STIMRY1B= 780 / Stim 1B right Y position STIMLX2A= 242 / Stim 2A left X position STIMLY2A= 618 / Stim 2A left Y position STIMRX2A= 16119 / Stim 2A right X position STIMRY2A= 627 / Stim 2A right Y position STIMLX2B= 251 / Stim 2B left X position STIMLY2B= 639 / Stim 2B left Y position STIMRX2B= 16121 / Stim 2B right X position STIMRY2B= 632 / Stim 2B right Y position ACTVL_1A= 800 / Active left edge of 1A (inclusive) ACTVR_1A= 15583 / Active right edge of 1A (inclusive) ACTVB_1A= 0 / Active bottom edge of 1A (inclusive) ACTVT_1A= 1023 / Active top edge of 1A (inclusive) ACTVL_1B= 800 / Active left edge of 1B (inclusive) ACTVR_1B= 15583 / Active right edge of 1B (inclusive) ACTVB_1B= 0 / Active bottom edge of 1B (inclusive) ACTVT_1B= 1023 / Active top edge of 1B (inclusive) ACTVL_2A= 800 / Active left edge of 2A (inclusive) ACTVR_2A= 15583 / Active right edge of 2A (inclusive) ACTVB_2A= 0 / Active bottom edge of 2A (inclusive) ACTVT_2A= 1023 / Active top edge of 2A (inclusive) ACTVL_2B= 800 / Active left edge of 2B (inclusive) ACTVR_2B= 15583 / Active right edge of 2B (inclusive) ACTVB_2B= 0 / Active bottom edge of 2B (inclusive) ACTVT_2B= 1023 / Active top edge of 2B (inclusive) FIFO_DRN= 3470 / IDS FIFO drain rate Data format: Empty FUSE.TLEDescription: Contains NORAD two-line elements characterizing the orbit of the FUSE satellite. There is typically one entry for each day of the mission since launch (1999 June 24). Data format: ASCII file; each record is terminated by a newline. Each two-line element consists of two records, followed by a blank line. GEOM_CAL (geom1a016.fit)This file contains corrections for detector geometric distortions. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains the X shift for each pixel in the detector needed to correct for distortions. Data format: Image 16384 × 1024 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. HDU 3Description: Contains the Y shift for each pixel in the detector needed to correct for distortions. Data format: Image 16384 × 1024 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. GRAT_CAL (grat005.fit)Thermal instabilities cause the FUSE gratings to wobble on orbital, diurnal, and precessional (60-day) timescales. An additional long-term, non-periodic drift is also apparent. For each of these timescales, this file contains a set of four file extensions, providing grating-motion corrections for each of spectrograph's four gratings. At present, only corrections for the long-term and orbital drifts are available. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains correction to position (in both X and Y) of the LiF1 spectrum (segments A and B) due to rotation of the LiF1 grating as a function of time throughout the mission. This motion is non-periodic. Data format: FITS binary table with 3 columns and any number of rows. At present, the Y correction is always zero.
HDU 3, 4, 5Same as HDU 2, but for the SiC1, LiF2, and SiC2 gratings, respectively. HDU 6Description: Contains correction to position (in both X and Y) of the LiF1 spectrum (segments A and B) due to rotation of the LiF1 grating as a function of orbital phase. The grating-motion solution depends on three parameters: beta angle (the angle between the target and the anti-sun vector), pole angle (the angle between the target and the orbit pole), and spacecraft roll angle (east of north, determined from the file-header keyword APER_PA). The pipeline routine cf_grating_motion compares the beta, pole, and roll angles of the spacecraft with the grid of values contained in this extension. Finding a match, it reads the corresponding XCOEFF and YCOEFF values (up to five of each) and uses them to generate pair of series (one each for X and Y) from which the motion corrections are computed. Data format: FITS binary table with 10 columns and any number of rows. Columns 7 and 8 contain arrays of Fourier coefficients. Columns 9 and 10 record Χ2 values for the fits to the measured X and Y coordinates of the Lyman β line.
HDU 7, 8, 9Same as HDU 6, but for the SiC1, LiF2, and SiC2 gratings, respectively. MIRR_CAL (mirr002.fit)Data in this file are used to correct for spectral drifts in the X dimension due to mirror motions during an exposure. The file was constructed assuming that the guide channel is LiF1, so its mirror motions are corrected by the spacecraft itself. Corrections are thus given only for the SiC1, LiF2, and SiC2 channels. Since 2005 June, the guide channel has been LiF2. In practice, this is not a problem, because the correction for LiF2 is zero. Also note that the corrections for SiC1 and SiC2 are identical (though opposite in sign). HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains corrections to the X positions of SiC1 photons. Data format: FITS image extension containing a single array of 100 numbers, representing the correction to be added to the observed X position of each SiC1 photon, computed once per minute for the 100-minute orbit of the FUSE satellite. HDU 3Same as HDU 2, but for LiF2 spectra. HDU 4Same as HDU 2, but for SiC2 spectra. PHAH_CAL (phah1a002.fit)For each aperture, this file lists the mean pulse height of photons obtained in TTAG mode as a function of time through the mission. This mean pulse height is assigned to HIST data so that it can receive a rudimentary walk correction. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains mean pulse heights for photons observed through the LiF HIRS aperture. Data format: FITS binary table with 2 columns and an arbitrary number of rows.
HDU 3, 4, 5Description: Contains mean pulse heights for photons observed through the LiF MDRS, LWRS, and PINH apertures. Data format: FITS binary table with 2 columns and an arbitrary number of rows.
HDU 6, 7, 8, 9Description: Contains mean pulse heights for photons observed through the SiC HIRS, MDRS, LWRS, and PINH apertures. Data format: FITS binary table with 2 columns and an arbitrary number of rows. PHAX_CAL (phax1a006.fit)This file contains the walk correction, used to correct for the misplacement of low-pulse-height photon events by the detector electronics. HDU 1Description: Contains the walk correction as a function of position X and pulse height PHA, stored as an image. We assume that walk is independent of Y. Data format: Image 16384 × 32 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. QUAL_CAL (qual1a020.fit)This file lists bad-pixels regions for the detector. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains locations and dimensions of the dead regions within the detector active area. The dead regions are specified as ellipses. The table contains the coordinates of the center of each ellipse and its semi-major and semi-minor axes. Data format: FITS binary table with 4 columns. (Data are actually stored as a single row; each table element is an array.)
RATE_CAL (rate1a002.fit)This file gives the stretch in the Y scale as a function of observed Y value and count rate. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Shifts are stored in a 102 × 31 image. Rows (i) are the observed Y value / 10. Column numbers (n) are related to the count rate as n=10 × [log10(count rate) - 1]. Thus, the shift for a Y value of 800 and a global count rate of 500 will be located in the array element [80,17]. Shift is applied according to the recipe new Y = old Y + image[i, n] Data format: Image 102 × 31 pixels. Data consist of real values. SAAC_CAL (saac004.fit or saac005.fit)These files contain the outer contour of the SAA used by the subroutine cf_screen_saa. By default, the pipeline uses saac004.fit. The file saac005.fit contains larger contours. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains a binary table with the longitude and latitude, marking the extent of the SAA. Data format: FITS binary table with 2 columns and 10 rows.
SPEC_CAL (spec002.fit)This file lists spectragraph parameters used by the subroutine cf_fpa_position, which shifts spectra in X to account for offsets of the focal-plane assembly. HDU 1Description: All data are stored in header keywords: ALPHALIF= 25.0000 / [deg] Spectrograph entrance angle (LiF) ALPHASIC= 24.0000 / [deg] Spectrograph entrance angle (SiC) SIGMALIF= 1869.20 / [A] Central groove spacing (LiF) SIGMASIC= 1734.00 / [A] Central groove spacing (SiC) DIAM = 1652.00 / [mm] Rowland circle diameter Data format: Empty STIM_CAL (stim1a002.fit)This file lists the X and Y coordinates of the stim pulses as a function of time. If the stim pulses for a particular data set are corrupted, cf_thermal_distort uses these values to estimate the thermal-distortion correction for that exposure. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains a binary table listing the X and Y coordinates of the stim pulses for various dates throughout the mission. Data format: FITS binary table with 5 columns and a variable number of rows.
TMXY_CAL (tmxy1a002.fit)This file corrects for slow drifts in the raw X and Y coordinates of the Lyman β line due to changes in the detector electronics. This feature appears only on detectors 1A and 2B; for the moment, no correction is available for detectors 1B and 2A. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains corrections to the X coordinate of a photon event as a function of its X coordinate and the MJD of the exposure. Data format: The detector drift in the X dimension has not yet been measured, so the X correction is zero. HDU 3Description: Contains corrections to the Y coordinate of a photon event as a function of its Y coordinate and the MJD of the exposure. Data format: Data are stored as a real-valued image 103 pixels wide and an arbitrary number of pixels high. Each row represents the correction for a particular MJD. The first column contains the MJD value for that row, the second column contains the shift for pixels with 0 <= Y < BIN_FACT, the third column for pixels with BIN_FACT <= Y < 2*BIN_FACT, etc. The value of BIN_FACT is stored as a keyword in the header of the HDU. To prevent pile-ups at boundaries, we interpolate between columns; however, we do not interpolate between rows. VOLT_CAL (volt1a009.fit)
HDU 1Description: All data are stored in header keywords: HVGOODLM= 0.850000 / HV/FULL < HVGOODLM is questionable HVBADLIM= 0.850000 / HV/FULL < HVBADLIM is bad MJD0 = 51403.84931 / [MJD] New voltage uplinked this date SAA0 = 70 / SAA voltage level FULL0 = 129 / Full voltage level MJD1 = 51416.68750 / [MJD] New voltage uplinked this date SAA1 = 70 / SAA voltage level FULL1 = 129 / Full voltage level Data format: Empty WAVE_CAL (wave1a023.fit)This file contains the wavelength of each detector pixel. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains the wavelength for each pixel in the LiF HIRS spectral image. Useful file header keywords include FPACXPOS= 117.000 / [microns] LiF FPA X position FPACZPOS= -34.7000 / [microns] LiF FPA Z position DISPAPIX= 0.00673558 / Average dispersion (Angstroms per pixel) W0 = 984.994 / [A] Recommended initial wavelength WMAX = 1085 / [A] Recommended final wavelength WPC = 0.0130000 / [A] Recommended wavelength per channel Data format: FITS binary table with 2 columns and 16384 rows:
HDU 3, 4, 5Description: Contains wavelengths for each pixel in the LiF MDRS, LWRS, and PINH spectral images. Data format: FITS binary table with 2 columns and 16384 rows. HDU 6, 7, 8, 9Description: Contains wavelengths for each pixel in the SiC HIRS, MDRS, LWRS, and PINH spectral images. Data format: FITS binary table with 2 columns and 16384 rows. WGTS_CAL (wgts1a011.fit)This file contains extraction weights, in the form of a spectral image, for use by the optimal-extraction routine. HDU 1Description: Contains keywords giving history of file. Data format: Empty HDU 2Description: Contains the extraction weights for each pixel in the LiF HIRS spectral image, assuming a point source. Header keyword WGT_CENT gives the Y centroid of this distribution. Data format: Image 16384 × 120 pixels. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. HDU 3, 4, 5Description: Contains extraction weights for each pixel in the LiF MDRS, LWRS, and PINH spectral images, assuming a point source. Data format: Image is 16384 pixels by a variable number of rows. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. HDU 6, 7, 8, 9Description: Contains extraction weights for each pixel in the SiC HIRS, MDRS, LWRS, and PINH spectral images for a point source. Data format: Image is 16384 pixels by a variable number of rows. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords. HDU 10-17Description: Same as HDU 2-9, except for an extended source. Data format: Image is 16384 pixels by a variable number of rows. Data consist of real values, stored as two-byte integers and scaled using the BSCALE and BZERO keywords.
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|