2.4 Headers and Keywords
ACS image headers for WFC, HRC, HRC-ACQ, and SBC observations have very similar formats. However, MAMA (SBC) headers require a slightly modified structure from the CCD format, and HRC-ACQ headers require several unique keywords.
ACS header keywords can be viewed in several ways. The example below demonstrates how to print the SCI extension header keyword CRVAL1 using the astropy Python package.
from astropy.io import fits
hdu = fits.open('j8cda1dsq_flt.fits')
hdr = hdu['sci',1].header
hdu.close()
print(hdr['CRVAL1'])
The output is 5.952775438936009.
ACS image header keywords are described in Tables 2.6 and 2.7. When printing the header, note that the keywords are grouped together by type, e.g., "Target Information," "Science Instrument Configuration," "Calibration Switches," and "Calibration Reference files." There are also convenience functions for querying header keywords. For more information, see the Astropy documentation.
Keywords in the image's primary header (FITS extension 0) contain parameter values that are common to the entire image dataset, and are given in Table 2.6.
Extension or group header keywords (FITS extensions > 0), as shown in Table 2.7, contain parameter values that are specific to the image group (however, many primary header keyword values are also accessible when querying an image group header).
Table 2.6: ACS primary header keywords (FITS extension 0). Some keywords are no longer in use, but are included for users who may have older data.
| KEYWORD | DESCRIPTION |
|---|---|
SIMPLE | Data conform to FITS standard (T/F) |
BITPIX | Bits per data value |
NAXIS | Number of data axes, always set to zero for the primary header |
EXTEND | FITS data may contain extensions (T/F) |
ORIGIN | FITS file originator |
NEXTEND | Number of standard extensions |
GROUPS | Image is in group format (T/F) |
DATE | Date this file was written (YYYY-MM-DD) |
FILENAME | Name of file |
FILETYPE | Type of data found in data file |
TELESCOP | Telescope used to acquire data |
INSTRUME | Identifier for instrument used to acquire data |
EQUINOX | Equinox of celestial coordinate system |
| DATA DESCRIPTION KEYWORDS (all detectors) | |
ROOTNAME | Rootname of the observation set |
IMAGETYP | Type of exposure identifier |
PRIMESI | Instrument designated as prime |
| TARGET INFORMATION (all detectors) | |
TARGNAME | Proposer's target name |
RA_TARG | Right ascension of the target (deg; J2000) |
DEC_TARG | Declination of the target (deg; J2000) |
| PROPOSAL INFORMATION (all detectors) | |
PROPOSID | PEP proposal identifier |
LINENUM | Proposal logsheet line number |
PR_INV_L | Last name of the principal investigator |
PR_INV_F | First name of the principal investigator |
PR_INV_M | Middle name/initial of the principal investigator |
| EXPOSURE INFORMATION (all detectors) | |
SUNANGLE | Angle between the Sun and V1 axis |
MOONANGL | Angle between the Moon and V1 axis |
SUN_ALT | Altitude of the Sun above Earth's limb |
FGSLOCK | Commanded FGS lock (FINE, COARSE, GYROS, UNKNOWN) |
GYROMODE | Number of gyros scheduled, T=3+OBAD (number of gyros available for use) |
REFFRAME | Guide star catalog version |
MTFLAG | Moving target flag (T=moving target) |
DATE-OBS | UT date of observation start (YYYY-MM-DD) |
TIME-OBS | UT time of observation start (HH:MM:SS) |
EXPSTART | Exposure start time (modified Julian date) |
EXPEND | Exposure end time (modified Julian date) |
EXPTIME | Exposure duration in seconds (calculated; exposure time as executed) |
TEXPTIME | Total exposure time for drizzled product |
DARKTIME | Total integration time for detector dark current in seconds (calculated) |
EXPFLAG | Exposure interruption indicator |
| Data quality comments. These keywords are populated if there are problems with the exposure. |
| POINTING INFORMATION (all detectors) | |
PA_V3 | Position angle of the V3-axis of HST (deg) |
| TARGET OFFSETS (all detectors) | |
POSTARG1 | POSTARG in axis 1 direction |
POSTARG2 | POSTARG in axis 2 direction |
| DIAGNOSTIC KEYWORDS (all detectors) | |
OPUS_VER | OPUS software system version number |
CSYS_VER | Calibration software system version number |
CAL_VER | calacs version number |
PROCTIME | Pipeline processing time (modified Julian date) |
| SCIENCE INSTRUMENT CONFIGURATION (all detectors except where noted) | |
OBSTYPE | Observation type (imaging, spectroscopic, coronagraphic) |
OBSMODE | Operating mode |
CTEIMAGE | Type of charge transfer image, if applicable |
SCLAMP | Lamp status: NONE or name of lamp which is on |
NRPTEXP | Number of repeat exposures in set (default=1) |
SUBARRAY | Data from a subarray (T) or full frame (F) |
DETECTOR | Detector in use: WFC, HRC, or SBC |
FILTER1 | Element selected from filter wheel 1 |
FW1OFFST | Computed filter wheel offset |
FW1ERROR | Filter wheel position error flag |
FILTER2 | Element selected from filter wheel 2 |
FW2OFFST | Computer filter wheel offset |
FW2ERROR | Filter wheel position error flag |
FWSOFFST | Computed filter wheel offset |
FWSERROR | Filter wheel position error flag |
LRFWAVE | Proposed linear ramp filter wavelength |
APERTURE | Aperture name |
PROPAPER | Proposed aperture name |
DIRIMAGE | Direct image for grism of prism exposure |
CTEDIR | CTE measurement direction (serial or parallel; CCDs only) |
CRSPLIT | Number of cosmic ray split exposures (CCDs only) |
| MAMA OFFSETS (SBC only) | |
MOFFSET1 | Axis 1 MAMA offset (low-res pixels) |
MOFFSET2 | Axis 2 MAMA offset (low-res pixels) |
| LOCAL RATE CHECK IMAGE (SBC only) | |
LRC_XSTS | Local rate check image exists (T/F) |
LRC_FAIL | Local rate check failed (T/F) |
| CALIBRATION SWITCHES: PERFORM, OMIT (all detectors except where noted) | |
STATFLAG | Calculate statistics (not used; statistics are always calculated by calacs) |
WRTERR | Write out error array extension (not used; always true for calacs) |
DQICORR | Data quality initialization |
ATODCORR | Correct for analog-to-digital conversion errors (CCDs only; not used by calacs) |
BLEVCORR | Subtract bias level computed from overscan image (CCDs only) |
BIASCORR | Subtract 2-D bias image (CCDs only) |
| Post-flash correction (CCDs only) |
CRCORR | Combine observations to reject cosmic rays (CCDs only) |
EXPSCORR | Process individual observations are cosmic ray rejection (CCDs only) |
SHADCORR | Apply shutter shading correction (CCDs only; always set to OMIT for ACS) |
GLINCORR | Correct for global detector non-linearities (SBC only) |
LFLGCORR | Flag pixels for local and global non-linearities (SBC only) |
PCTECORR | CTE correction (always set to OMIT for non-WFC exposures) |
DARKCORR | Subtract dark image |
FLATCORR | Flat-field data |
PHOTCORR | Populate photometric header keywords |
RPTCORR | Add individual repeat observations |
DRIZCORR | Drizzle processing |
SINKCORR | Flag sink pixels (affects WFC only since 2015) |
| CALIBRATION REFERENCE FILES (all detectors except where noted) | |
BPIXTAB | Bad pixel table |
MLINTAB | MAMA linearity correction table (SBC only) |
CCDTAB | CCD calibration parameter table (CCDs only) |
ATODTAB | Analog-to-digital correction file (CCDs only; not used by calacs) |
OSCNTAB | CCD overscan table (CCDs only) |
BIASFILE | 2-D bias image file name (CCDs only) |
FLSHFILE | Post-flash correction file (CCDs only) |
CRREJTAB | Cosmic ray rejection parameters (CCDs only) |
SHADFILE | Shutter shading correction file (CCDs only; not used by calacs) |
PCTETAB | CTE correction table (always set to N/A for non-WFC exposures) |
DRKCFILE | CTE-corrected dark image file name (always set to N/A for non-WFC exposures) |
DARKFILE | Dark image file name |
PFLTFILE | Pixel-to-pixel flat-field name |
DFLTFILE | Delta flat-field name |
LFLTFILE | Low-order flat-field name |
PHOTTAB | Photometric throughput table (not used by calacs) |
GRAPHTAB | HST graph table (not used by calacs) |
COMPTAB | HST components table (not used by calacs) |
IDCTAB | Image distortion correction table |
DGEOFILE | Distortion correction image (not used by AstroDrizzle for calacs) |
MDRIZTAB | AstroDrizzle parameter table |
CFLTFILE | Coronagraphic spot flat-field name |
SPOTTAB | Coronagraphic spot offset table |
IMPHTTAB | Image photometry table |
D2IMFILE | Column correction reference files |
NPOLFILE | Non-polynomial offsets reference files |
SKNCFILE | Map of sink pixels (affects WFC only since 2015) |
SATUFILE | Full-well saturation level map |
| COSMIC RAY REJECTION ALGORITHM PARAMETERS (WFC, HRC, HRC ACQ) | |
MEANEXP | Reference exposure time for parameters |
SCALENSE | Multiplicative scale factor applied to noise |
INITGUES | Initial guess method (MIN or MED) |
SKYSUB | Sky value subtracted (MODE or NONE) |
SKYSUM | Sky level from the sum of all constituent images |
CRSIGMAS | Statistical rejection criteria |
CRRADIUS | Rejection propagation radius (pixels) |
CRTHRESH | Rejection propagation threshold |
BADINPQD | Data quality flag bits to reject |
REJ_RATE | Rate at which pixels are affected by cosmic rays |
CRMASK | Flag cosmic ray-rejected pixels in input files (T/F) |
| OTFR Keywords (all detectors) | |
T_SGSTAR | OMS calculated guide star control |
| PATTERN KEYWORDS (all detectors) | |
PATTERN1 | Primary pattern type |
P1_SHAPE | Primary pattern shape |
P1_PURPS | Primary pattern purpose |
P1_NPTS | Number of points in primary pattern |
P1_PSPAC | Point spacing for primary pattern (arcsec) |
P1_LSPAC | Line spacing for primary pattern (arcsec) |
P1_ANGLE | Angle between sides of parallelogram pattern (deg) |
P1_FRAME | Coordinate frame of primary pattern |
P1_ORINT | Orientation of pattern to coordinate frame (deg) |
P1_CENTR | Center pattern relative to pointing (yes/no) |
PATTSTEP | Position number of this point in the pattern |
| POST-FLASH PARAMETERS (WFC, HRC, HRC ACQ) | |
FLASHDUR | Exposure time in seconds (0.1 to 409.5) |
FLASHCUR | Post-flash current (OFF, LOW, MED, HIGH) |
FLASHSTA | Status (SUCCESSFUL, ABORTED, NOT PERFORMED) |
SHUTRPOS | Shutter position (A or B) |
| ENGINEERING PARAMETERS (WFC, HRC, HRC ACQ) | |
CCDAMP | CCD amplifier readout configuration |
CCDGAIN | Commanded gain of CCD (electrons/DN) |
CCDOFSTA | Commanded CCD bias offset for amplifier A |
CCDOFSTB | Commanded CCD bias offset for amplifier B |
CCDOFSTC | Commanded CCD bias offset for amplifier C |
CCDOFSTD | Commanded CCD bias offset for amplifier D |
JWROTYPE | ASIC WFC readout type (DS_int for dual-slope integration or CLAMP for clamp-and-sample) |
| CALIBRATED ENGINEERING PARAMETERS (WFC, HRC, HRC ACQ) | |
ATODGNA | Calibrated gain for amplifier A (electrons/DN) |
ATODGNB | Calibrated gain for amplifier B (electrons/DN) |
ATODGNC | Calibrated gain for amplifier C (electrons/DN) |
ATODGND | Calibrated gain for amplifier D (electrons/DN) |
READNSEA | Calibrated read noise for amplifier A (electrons) |
READNSEB | Calibrated read noise for amplifier B (electrons) |
READNSEC | Calibrated read noise for amplifier C (electrons) |
READNSED | Calibrated read noise for amplifier D (electrons) |
BIASLEVA | Bias level for amplifier A (electrons) |
BIASLEVB | Bias level for amplifier B (electrons) |
BIASLEVC | Bias level for amplifier C (electrons) |
BIASLEVD | Bias level for amplifier D (electrons) |
| TARGET ACQUISITION PARAMETERS (HRC ACQ only) | |
AUTHOR | Headerlet created by this user |
CATALOG | Astrometric catalog used for headerlet solution |
DESCRIP | Short description of headerlet |
DESTIM | Destination observation rootname |
HDRNAME | Headerlet name |
NMATCH | Number of sources used for headerlet solution |
RMS_DEC | RMS in declination at reference pixel of headerlet solution |
RMS_RA | RMS in right ascension at reference pixel of headerlet solution |
| ASSOCIATION KEYWORDS (all detectors) | |
ASN_ID | Unique identifier assigned to association |
ASN_TAB | Name of the association table |
ASN_MTYP | Role of the member in the association |
CRDS_CTX | Master calibration reference system file |
CRDS_VER | Calibration reference system version number |
| CTE CORRECTION KEYWORDS (WFC only) | |
CTE_NAME | CTE algorithm name |
CTE_VER | CTE algorithm version |
CTEDATE0 | Date of ACS installation |
PCTETRSH | CTE over subtraction threshold |
CTEDATE1 | Date of CTE model pinning |
PCTEFRAC | CTE scaling factor |
PCTELEN | Maximum length of CTE trail |
PCTERNOI | Read noise amplifier clip limit |
PCTENFOR | Number of iterations in forward model |
PCTENPAR | Number of iterations in parallel transfer |
FIXROCR | Fix readout cosmic rays |
| ASTRODRIZZLE KEYWORDS (all detectors) | |
UPWCSVER | Version of STWCS used to update the WCS |
PYWCSVER | Version of PYWCS used to update the WCS |
DISTNAME | Names of all distortion model components used |
SIPNAME | Specific polynomial distortion model |
RULESVER | Version ID for header keyword rules file |
BLENDVER | Version of blendheader software used |
RULEFILE | Name of header keyword rules file |
NDRIZNUM | Number of images drizzled onto output |
D???OUUN | Units of output image (counts or counts/second) |
D???MASK | Input weighting image |
D???FVAL | Fill value for zero weight output pixels |
D???KERN | Form of weight distribution kernel |
D???ISCL | Default IDCTAB pixel size (arcsec) |
D???COEF | Source of coefficients |
D???SCAL | Pixel size of output image (arcsec) |
D???GEOM | Source of geometric information |
D???DATA | Input image data |
D???OUWE | Output weighting image |
D???OUCO | Output context image |
D???DECP | Input image exposure time (seconds) |
D???WKEY | Input image WCS version used |
D???OUDA | Output data image |
D???VER | Drizzle task version number |
D???WTSC | Weighting factor for input image |
D???PIXF | Linear size of drop |
| DEPRECATED KEYWORDS (all detectors, in alphabetical order) | |
ACQTYPE | Type of acquisition |
BIASLEV | CCD bias level used to process acquisition exposure |
CCDBIASS | CCD bias subtracted from target acquisition image (yes/no) |
CENTMETH | Target acquisition centering method |
CHECKBOX | Size of checkbox for finding algorithm |
CRELIM | Perform cosmic ray rejection in acquisition |
Table 2.7: ACS extension header keywords (SCI, ERR, and DQ FITS extensions).
| KEYWORD | DESCRIPTION |
|---|---|
| ASSOCIATION KEYWORDS (all detectors) | |
XTENSION | Extension type |
NAXIS1 | Length of first data axis |
NAXIS2 | Length of second data axis |
PCOUNT | Required keyword; must = 0 |
GCOUNT | Required keyword; must = 1 |
EXTNAME | Extension name |
EXTVER | Extension version number |
INHERIT | Inherit the primary header |
EXPNAME | Exposure identifier |
DATAMIN | Minimum data value |
DATAMAX | Maximum data value |
BUNIT | Brightness units (counts, electrons, electrons/second) |
NPIX1 | Length of constant array axis 1 |
NPIX2 | Length of constant array axis 2 |
PIXVALUE | Values of pixels in constant array |
BSCALE | Scale factor for array value to physical value |
BZERO | Physical value for an array value of zero |
| WFC CCD CHIP IDENTIFICATION (WFC only) | |
CCDCHIP | CCD chip (1 or 2) |
| WORLD COORDINATE SYSTEM AND RELATED PARAMETERS (all detectors) | |
WCSAXES | Number of World Coordinate System axes |
CRPIX1 | x-coordinate of reference pixel |
CRPIX2 | y-coordinate of reference pixel |
CRVAL1 | First axis value at reference pixel |
CRVAL2 | Second axis value at reference pixel |
CTYPE1 | The coordinate type for the first axis |
CTYPE2 | The coordinate type for the second axis |
CD1_1 | Partial of first axis coordinate with respect to x |
CD1_2 | Partial of first axis coordinate with respect to y |
CD2_1 | Partial of second axis coordinate with respect to x |
CD2_2 | Partial of second axis coordinate with respect to y |
LTV1 | Offset in x to subsection start (x-coordinate of the first science pixel in the SCI array) |
LTV2 | Offset in y to subsection start (y-coordinate of the first science pixel in the SCI array) |
RAW_LTV1 | Original offset in x to subsection start (x-coordinate of the first science pixel in the SCI array) |
RAW_LTV2 | Original offset in y to subsection start (y-coordinate of the first science pixel in the SCI array) |
LTM1_1 | Reciprocal of sampling rate in x (the reference pixel size in units of current pixel size) |
LTM2_2 | Reciprocal of sampling rate in y (the reference pixel size in units of current pixel size) |
ORIENTAT | Position angle of image y axis (degrees E of N) |
RA_APER | Right ascension of aperture reference position |
DEC_APER | Declination of aperture reference position |
PA_APER | Position angle of reference aperture center (deg) |
VAFACTOR | Velocity aberration plate scale factor |
| READOUT DEFINITION PARAMETERS (all detectors) | |
CENTERA1 | Subarray axis 1 centerpoint in unbinned detector pixels |
CENTERA2 | Subarray axis 2 centerpoint in unbinned detector pixels |
SIZAXIS1 | Subarray axis 1 size in unbinned detector pixels |
SIZAXIS2 | Subarray axis 2 size in unbinned detector pixels |
BINAXIS1 | Axis 1 data bin size in unbinned detector pixels |
BINAXIS2 | Axis 2 data bin size in unbinned detector pixels |
| PHOTOMETRY KEYWORDS (all detectors) | |
PHOTMODE | Observation configuration |
PHOTFLAM | Inverse sensitivity (erg/cm2/Å/electron) |
PHOTZPT | ST magnitude zero points |
PHOTPLAM | Pivot wavelength (Angstroms) |
PHOTBW | RMS bandwidth of filter plus detector |
| DATA PACKET INFORMATION (all detectors) | |
FILLCNT | Number of segments containing fill value for which data were lost in transmission |
ERRCNT | Number of segments containing errors |
PODSPSFF | PODPS fill present (T/F) indicating if there are missing packets in the data stream. Missing packets are replaced with fill packets by OPUS to facilitate pipeline processing. |
STDCFFF | Science telemetry fill present (T/F) indicating if there were errors found in the science dataset at the Space Telescope Data Capture Facility. |
STDCFFP | Science telemetry fill pattern (hex) |
| ENGINEERING PARAMETERS (SBC only) | |
GLOBRATE | Global count rate |
GLOBLIM | Was global linearity level exceeded? |
MDECODT1 | MAMA JMDECODT pwd temperature from eng snap 1 (deg C; temperature at the start of observation) |
MDECODT2 | MAMA JMDECODT pwd temperature from eng snap 2 (deg C; temperature at the end of observation) |
| REPEATED EXPOSURES INFORMATION (WFC, HRC, HRC ACQ) | |
NCOMBINE | Number of image sets combined during cosmic ray rejection |
| ONBOARD COMPRESSION INFORMATION (WFC only) | |
WFCMPRSD | Was WFC data compressed? (T/F) |
CBLKSIZ | Size of compression block in 2 byte words |
LOSTPIX | Number of pixels lost due to buffer overflow |
COMPTYP | Compression type performed (Partial/Full/None) |
| IMAGE STATISTICS AND DATA QUALITY FLAGS (all detectors except where noted) | |
NGOODPIX | Number of good pixels |
SDQFLAGS | Serious data quality flags (bad pixels that are not included in calculations for header keyword image statistics, e.g., GOODMEAN, NGOODPIX, etc.) |
GOODMIN | Minimum value of good pixels |
GOODMAX | Maximum value of good pixels |
GOODMEAN | Mean value of good pixels |
SOFTERRS | Number of soft error pixels (DQF=1) |
SNRMIN | Minimum signal to noise of good pixels |
SNRMAX | Maximum signal to noise of good pixels |
SNRMEAN | Mean value of signal to noise of good pixels |
MEANDARK | Average of the dark values subtracted (electrons) |
MEANBLEV | Average of all bias levels subtracted (electrons; CCDs only) |
MEANFLSH | Mean number of counts in post-flash exposure (electrons; CCDs only) |
MDRIZSKY | Sky value computed by AstroDrizzle |
| DISTORTION CORRECTION PARAMETERS (all detectors) | |
A_0_2, B_0_2, A_1_1, B_1_1, A_2_0, B_2_0, A_0_3, B_0_3, A_1_2, B_1_2, A_2_1, B_2_1, A_3_0, B_3_0, A_0_4, B_0_4, A_1_3, B_1_3, A_2_2, B_2_2, A_3_1, B_3_1, A_4_0, B_4_0, A_3_2, B_3_2, B_1_4, B_2_3, B_0_5, A_5_0, A_4_1, B_4_1, B_5_0, A_1_4, A_0_5, A_2_3 | Non-linear or high-order polynomial coefficients in the SIP convention describe the geometric distortion model for each image group. They are present for use by SIP-enabled code such as DS9 and for use by the pipeline software and AstroDrizzle. For more information on the SIP model, see Shupe et al. 2005. |
A_ORDER, B_ORDER | Order of the polynomial used to describe geometric distortion corrections |
IDCSCALE | Pixel scale in the IDCTAB table |
IDCXREF | Reference pixel location in x as specified by the IDCTAB |
IDCYREF | Reference pixel location in y as specified by the IDCTAB |
IDCV2REF | Reference pixel V2 position as derived from the IDCTAB reference table |
IDCV3REF | Reference pixel V3 position as derived from the IDCTAB reference table |
IDCTHETA | Orientation of the detector's Y-axis relative to V3 axis, as derived from the IDCTAB reference table |
OCX10 | Linear distortion term without image plate scale, directly from distortion model (IDCTAB) |
OCX11 | Linear distortion term without image plate scale, directly from distortion model (IDCTAB) |
OCY10 | Linear distortion term without image plate scale, directly from distortion model (IDCTAB) |
OCY11 | Linear distortion term without image plate scale, directly from distortion model (IDCTAB) |
D2IMEXT | Reference file used by updatewcs to create a D2IMARR extension, which holds the column or row corrections |
D2IMERR1 | Maximum error of NPOL correction for axis 1 |
D2IMDIS1 | Detector-to-image correction type for axis 1 |
D2IMERR2 | Maximum error of NPOL correction for axis 2 |
D2IMDIS2 | Detector-to-image correction type for axis 2 |
D2IM1.AXIS.1, D2IM1.AXIS.2, D2IM1.EXTVER, D2IM1.NAXES, D2IM2.AXIS.1, D2IM2.AXIS.1, D2IM2.EXTVER, D2IM2.NAXES | WCS NPOL correction parameters |
WCSNAMEO | WCS solution label |
WCSAXESO | Number of WCS axes |
CRPIX1O, CRPIX2O, CDELT1O, CDELT2O, CUNIT1, CUNIT1O, CUNIT2, CUNIT2O, CTYPE1O, CTYPE2O, CRVAL1O, CRVAL2O, LONPOLE, LONPOLEO, LATPOLE, LATPOLEO, CD1_1O, CD1_2O, CD2_1O, CD2_2O, CDELT1, CDELT2, RADESYS, RADESYSO | WCS solution parameters |
CDERR1, CPDIS1, CDERR2, CPDIS2, CPERR1, CPERR2 DP1.AXIS.1, DP1.AXIS.2, DP1.EXTVER, DP1.NAXES, DP2.AXIS.1, DP2.AXIS.2, DP2.EXTVER, DP2.NAXES | Distortion solution parameters, if performed |
NPOLEXT | NPOLFILE used, if applicable |
TDD_CTB | WFC time-dependent distortion parameter (skew angle in Y-axis) |
TDD_CXB | WFC time-dependent distortion parameter (scale in X-axis) |
| TARGET ACQUISITION KEYWORDS (HRC ACQ only) | |
TG_ENAME | Target science data extension name |
TG_EVER | Target science data extension version number |
| DEPRECATED KEYWORDS (all detectors, sorted alphabetically) | |
APERA1 | FSW located subarray axis 1 coordinate of aperture |
APERA2 | FSW located subarray axis 2 coordinate of aperture |
APERLKA1 | Axis 1 detector pixel of acquisition aperture center |
APERLKA2 | Axis 2 detector pixel of acquisition aperture center |
AXISCORR | Axis to which the DET2IM correction is applied |
BOPOFFA1 | Axis 1 offset object moved off aperture (arcsec) |
BOPOFFA2 | Axis 2 offset object moved off aperture (arcsec) |
MAXCHCNT | Counts in the brightest checkbox |
OCD1_1 | Partial of first axis coordinate with respect to x |
OCD1_2 | Partial of first axis coordinate with respect to y |
OCD2_1 | Partial of second axis coordinate with respect to x |
OCD2_2 | Partial of second axis coordinate with respect to y |
OCRPIX1 | x-coordinate of reference pixel |
OCRPIX2 | y-coordinate of reference pixel |
OCRVAL1 | First axis value at reference pixel |
OCRVAL2 | Second axis value at reference pixel |
OCRTYPE1 | The coordinate type for the first axis |
OCRTYPE2 | The coordinate type for the second axis |
ONAXIS1 | x-axis length |
ONAXIS2 | y-axis length |
OORIENTA | Position angle of image y-axis (deg E of N) |
TARGA1 | FSW located subarray axis 1 coordinate of target |
TARGA2 | FSW located subarray axis 2 coordinate of target |
TDDALPHA | WFC time-dependent distortion coefficient alpha |
| WFC time-dependent distortion coefficient beta |
TDD_CTA | WFC time-dependent distortion coefficient alpha |
TDD_CYA | WFC time-dependent distortion coefficient alpha |
TDD_CYB | WFC time-dependent distortion coefficient alpha |
TDD_CXA | WFC time-dependent distortion coefficient alpha |
| WCSDATE | Time WCS keywords were copied |
| Hubble Advanced Products (HAP) Related Keywords in the SCI extension of some *_flt.fits/ *_flc.fits images. | |
| (Only full-frame WFC images contain these keywords.) | |
| WCSTYPE | Coordinate system description |
| RMS_RA | RMS in RA for fit (milliarcseconds) |
| RMS_DEC | RMS in DEC for fit (milliarcseconds) |
| CRDER1 | RMS of fit in RA (degrees) |
| CRDER2 | RMS of fit in DEC (degrees) |
| NMATCHES | Number of matched sources in fit |
| FITGEOM | Geometry used for fitting |
| HDRNAME | Label for headerlet solution |