2.2 ACS File Structure

The ACS calibration pipeline assembles data received from HST into datasets, applies standard calibrations (so that calibrated image header keyword values can be entered in the Archive database), and stores uncalibrated datasets in the HST Data Archive. When a user requests data, it is fetched from the MAST static archive unless newer versions of the pipeline and/or calibration reference files are present. In the latter case, the requested data will be moved to the top of the reprocessing queue.

Data from the Archive arrives as multi-extension FITS files that have three main categories, as listed below (see Figure 2.1 for a graphical representation of this information). Single quotes around the extension names are required in Python usage.

  1. Global header extension (PRIMARY): this is always in extension [0], and contains a selection of header keyword values applicable to all information in the FITS file.
  2. Science image ('SCI'), error array ('ERR'), and data quality array ('DQ') extensions:
    1. HRC and SBC are single-detector channels. For these channels, the science image is in extension [1] or ['SCI',1], error array in extension [2] or ['ERR',1], and data quality array in extension [3] or ['DQ',1].
    2. WFC data comes from two chips, each with its own science, error, and data quality arrays. For WFC2, the science image is in extension [1] or ['SCI',1], error array in extension [2] or ['ERR',1], and data quality array in extension [3] or ['DQ',1]. For WFC1, the science image is in extension [4] or ['SCI',2], error array in extension [5] or ['ERR',2], and data quality array in extension [6] or ['DQ',2]. See Figure 2.2 for a visual representation of the WFC chips projected onto the V2,V3 axis.
  3. AstroDrizzle extensions:
    1. Drizzled data from the pipeline have the suffix drz.fits, and additionally drc.fits for WFC CTE-corrected data. These products are delivered as multi-extension FITS files with three image data extensions: science image ['SCI'], weight image ['WHT'], and context image ['CTX']. However, AstroDrizzle also adds new FITS extensions to the flt.fits/flc.fits and drz.fits/drc.fits files, as summarized below. For more information on drizzled data, please refer to the Drizzlepac Handbook.
    2. For flt.fits/flc.fits images: during OTFR processing, AstroDrizzle updates the WCS of these images with distortion corrections. Linear distortion corrections (scale, rotation, and time-dependent skew) are incorporated into the CD-Matrix. Coefficients for higher order polynomial functions that describe the distortion corrections are stored as SIP1 header keyword values. Some distortion corrections, however, cannot be expressed as equations and have to be stored in array form as FITS extensions.
    3. The ['D2IMARR'] fits extensions are tabular data required only for WFC, with one extension per chip axis. They are filter-independent corrections for the CCD pixel-grid irregularities resulting from the manufacturing process and contain both X and Y corrections for each WFC CCD chip.
    4. The ['WCSDVARR'] fits extensions, with one extension per chip axis, hold tabular data which describe small-scale distortions due to filter-dependent non-polynomial distortion corrections which include both X and Y corrections for each WFC CCD chip. Therefore, a WFC flt.fits/flc.fits image has four ['WCSDVARR'] extensions while HRC and SBC only have two ['WCSDVARR'] extensions.
    5. If the data were reprocessed with a new distortion correction reference file, a FITS extension called ['WCSCORR'] is added that contains a history of WCS changes.
    6. Several ['HEADERLET'] FITS extensions containing WCS transformations that can be applied as the primary WCS. For more detailed information please consult the Hubble Advanced Products (HAP) headerlets page.
    7. For drz.fit/drc.fits images: a fourth extension has been added, called ['HDRTAB'], which is a compilation of important header keywords that have unique values for each input image.

Figure 2.1: Data Format for Calibrated and Drizzled ACS Modes



For calibrated science data, WFC1 (chip 1) corresponds to extension ['SCI',2] or [4]. Hubble Advanced Products (HAP) images now contain an additional variable number of extensions containing World Coordinate System (WCS) headerlets for various alignment solutions.


The number of headerlets may vary from image to image depending on what has been done to it. Here below is the header listing I did of a standard *_flc.fits file and for comparison farther below, the header listing of a standard *_drc.fits file.

Python INPUT:

*_flc.fits image listing of header groups:
from astropy.io import fits

fits_image_filename = ('jcsz32diq_flc.fits')

hdul = fits.open(fits_image_filename)

hdul.info()

hdul.close()

Python OUTPUT:

Listing of header groups:
Filename: jcsz32diq_flc.fits
No.    Name         Type      Cards   Dimensions   Format
0    PRIMARY     PrimaryHDU     289   ()             
1    SCI         ImageHDU       241   (4096, 2048)   float32  
2    ERR         ImageHDU        53   (4096, 2048)   float32  
3    DQ          ImageHDU        45   (4096, 2048)   int16  
4    SCI         ImageHDU       239   (4096, 2048)   float32  
5    ERR         ImageHDU        53   (4096, 2048)   float32  
6    DQ          ImageHDU        45   (4096, 2048)   int16  
7    D2IMARR     ImageHDU        16   (64, 32)     float32  
8    D2IMARR     ImageHDU        16   (64, 32)     float32  
9    D2IMARR     ImageHDU        16   (64, 32)     float32  
10   D2IMARR     ImageHDU        16   (64, 32)     float32  
11   WCSDVARR    ImageHDU        16   (64, 32)     float32  
12   WCSDVARR    ImageHDU        16   (64, 32)     float32  
13   WCSDVARR    ImageHDU        16   (64, 32)     float32  
14   WCSDVARR    ImageHDU        16   (64, 32)     float32  
15   HDRLET      NonstandardExtHDU     18   ()             
16   HDRLET      NonstandardExtHDU     26   ()             
17   WCSCORR     BinTableHDU     59   14R x 24C    [40A, I, A, 24A, 24A, 24A, 24A, D, D, D, D, D, D, D, D, 24A, 24A, D, D, D, D, J, 40A, 128A]  
18   HDRLET      NonstandardExtHDU     26   ()             
19   HDRLET      NonstandardExtHDU     26   ()             


Similarly, one may list the header groups of a *_drc.fits image.

Python INPUT:

Code to list *_drc.fits image header groups
from astropy.io import fits

fits_image_filename = ('jcsz32010_drc.fits')

with fits.open(fits_image_filename) as hdu1:

    hdu1.info()

Python OUTPUT:

*_drc.fits header listing of groups
Filename: jcsz32010_drc.fits
No.    Name         Type      Cards   Dimensions   Format
0    PRIMARY     PrimaryHDU     856   ()              
1    SCI         ImageHDU        81   (4222, 4334)   float32   
2    WHT         ImageHDU        44   (4222, 4334)   float32   
3    CTX         ImageHDU        37   (4222, 4334)   int32   
4    HDRTAB      BinTableHDU    633   8R x 312C    [9A, 3A, K, D, D, D, D, D, D, D, D, D, D, D, D, D, K, 8A, 9A, 7A, 18A, 4A, D, D, D, D, 3A, D, D, D, D, D, D, D, D, D, D, D, D, K, 8A, 23A, D, D, D, D, K, K, K, 8A, K, 23A, 9A, 20A, K, 4A, K, D, K, K, K, K, 23A, D, D, D, D, K, K, 3A, 3A, 4A, 4A, L, D, D, D, 3A, 1A, K, D, D, D, 13A, 3A, 4A, 4A, 12A, 12A, 23A, 8A, 23A, 10A, 10A, D, D, 3A, 3A, 23A, 4A, 8A, 7A, 23A, D, K, D, 6A, 9A, 8A, D, D, L, 4A, 18A, 3A, K, 5A, 7A, 3A, D, 13A, 8A, 4A, 3A, L, K, L, K, L, K, K, D, D, D, D, D, D, 3A, 1A, D, 23A, D, D, D, 3A, 23A, L, 1A, 3A, 6A, D, 3A, 6A, K, D, D, D, D, D, D, D, D, D, D, 23A, D, D, D, D, 3A, D, D, D, 1A, K, K, K, K, K, K, 23A, K, 5A, 7A, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, 13A, D, 24A, 23A, D, 1A, 1A, D, K, D, D, 1A, 1A, D, 4A, K, D, K, 8A, D, D, D, D, D, 23A, 23A, D, 8A, D, 29A, D, 3A, D, L, D, D, 3A, 8A, 4A, 1A, D, 8A, K, 1A, 1A, 1A, 1A, D, D, D, D, D, D, 4A, D, 4A, D, 4A, K, 4A, 3A, 1A, L, K, K, 1A, D, D, D, D, K, 3A, L, L, 6A, L, D, D, 9A, D, D, 3A, 8A, 1A, D, K, D, L, 30A, L, 5A, 4A, K, D, D, D, D, D, D, D, D, D, D, D, D, D, D, 8A, 8A, 3A, 3A]   


One can also look for a specific keyword in a specific extension, such as the GAIN value in the Group 0 header extension here.


Python INPUT:


Code to find specific keyword in specific header group, in this case GAIN in Group 0
from astropy.io import fits

fits_image_filename = ('jcsz32010_drc.fits')

with fits.open(fits_image_filename) as hdu1:

    print(hdu1[0].header['CCDGAIN'])

Python INPUT:

Output GAIN value in Group 0 header
2.0


One can also look at the full header contents for a specific extension, in this case below, the Group 0 extension.

Python INPUT:

Full listing of keywords and their values from Group 0 header
from astropy.io import fits

fits_image_filename = 'jcsz32010_drc.fits'

with fits.open(fits_image_filename) as hdu1:

    hdr = hdu1[0].header

hdr

Python OUTPUT:

Full Group 0 header keyword and value listing
 
SIMPLE  =                    T / conforms to FITS standard                      
BITPIX  =                    8 / array data type                                
NAXIS   =                    0 / number of array dimensions                     
EXTEND  =                    T                                                  
COMMENT   FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT   and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H 
                                                                                
TELESCOP= 'HST'                / telescope used to acquire data                 
INSTRUME= 'ACS   '             / identifier for instrument used to acquire data 
                                                                                
              / DATA DESCRIPTION KEYWORDS                                       
                                                                                
IMAGETYP= 'EXT               ' / type of exposure identifier                    
PRIMESI = 'ACS   '             / instrument designated as prime                 
                                                                                
              / TARGET INFORMATION                                              
                                                                                
TARGNAME= 'ABELL-370                      ' / proposer's target name            
                                                                                
              / PROPOSAL INFORMATION                                            
                                                                                
PROPOSID=                14038 / PEP proposal identifier                        
                                                                                
              / EXPOSURE INFORMATION                                            
                                                                                
SUNANGLE=            92.396057 / angle between sun and V1 axis                  
MOONANGL=           101.841713 / angle between moon and V1 axis                 
SUN_ALT =            93.186295 / altitude of the sun above Earth's limb         
FGSLOCK = 'FINE              ' / commanded FGS lock (FINE,COARSE,GYROS,UNKNOWN) 
GYROMODE= 'T'                  / number of gyros scheduled, T=3+OBAD            
                                                                                
DATE-OBS= '2016-01-25'         / UT date of start of observation (yyyy-mm-dd)   
EXPSTART=   5.741240408115E+04 / exposure start time (Modified Julian Date)     
EXPEND  =       57412.49923216 / exposure end time (Modified Julian Date)       
EXPTIME =               5146.0 / exposure duration (seconds)--calculated        
TEXPTIME=               5146.0                                                  
EXPFLAG = 'NORMAL       '      / Exposure interruption indicator                
                                                                                
DARKTIME=        1.2284331E+03 / fiducial pixel dark time (secs)                
                                                                                
              / POINTING INFORMATION                                            
                                                                                
                                                                                
              / TARGET OFFSETS (POSTARGS)                                       
                                                                                
POSTARG1=             0.677630 / POSTARG in axis 1 direction                    
POSTARG2=            10.565430 / POSTARG in axis 2 direction                    
                                                                                
              / DIAGNOSTIC KEYWORDS                                             
                                                                                
AWSYSVER= 'v0.4.33 '           / cloud infrastructure package version           
AWSDPVER= 'v0.2.16 '           / cloud docker image version                     
CSYS_VER= 'caldp_20211129'     / calibration software system version id         
                                                                                
              / SCIENCE INSTRUMENT CONFIGURATION                                
                                                                                
OBSTYPE = 'IMAGING       '     / observation type - imaging or spectroscopic    
OBSMODE = 'ACCUM     '         / operating mode                                 
CTEIMAGE= 'NONE'               / type of Charge Transfer Image, if applicable   
SCLAMP  = 'NONE          '     / lamp status, NONE or name of lamp which is on  
NRPTEXP =                    1 / number of repeat exposures in set: default 1   
SUBARRAY=                    F / data from a subarray (T) or full frame (F)     
DETECTOR= 'WFC'                / detector in use: WFC, HRC, or SBC              
FILTER1 = 'F606W             ' / element selected from filter wheel 1           
FILTER2 = 'CLEAR2L           ' / element selected from filter wheel 2           
FW1OFFST=                    0 / computed filter wheel offset                   
FW1ERROR=                    F / filter wheel position error flag               
FW2OFFST=                -4320 / computed filter wheel offset                   
FW2ERROR=                    T / filter wheel position error flag               
FWSOFFST=                    0 / computed filter wheel offset                   
FWSERROR=                    F / filter wheel position error flag               
LRFWAVE =             0.000000 / proposed linear ramp filter wavelength         
APERTURE= 'WFCENTER        '   / aperture name                                  
PROPAPER= 'WFCENTER        '   / proposed aperture name                         
DIRIMAGE= 'NONE     '          / direct image for grism or prism exposure       
CTEDIR  = 'NONE    '           / CTE measurement direction: serial or parallel  
CRSPLIT =                    1 / number of cosmic ray split exposures           
                                                                                
              / CALIBRATION SWITCHES: PERFORM, OMIT, COMPLETE                   
                                                                                
WRTERR  =                    T / write out error array extension                
DQICORR = 'COMPLETE'           / data quality initialization                    
ATODCORR= 'OMIT    '           / correct for A to D conversion errors           
BLEVCORR= 'COMPLETE'           / subtract bias level computed from overscan img 
BIASCORR= 'COMPLETE'           / Subtract bias image                            
FLSHCORR= 'OMIT    '           / post flash correction                          
CRCORR  = 'OMIT    '           / combine observations to reject cosmic rays     
EXPSCORR= 'COMPLETE'           / process individual observations after cr-reject
SHADCORR= 'OMIT    '           / apply shutter shading correction               
DARKCORR= 'COMPLETE'           / Subtract dark image                            
FLATCORR= 'COMPLETE'           / flat field data                                
PHOTCORR= 'COMPLETE'           / populate photometric header keywords           
DRIZCORR= 'COMPLETE'           / drizzle processing                             
SINKCORR= 'COMPLETE'           / flag sink pixels                               
                                                                                
              / CALIBRATION REFERENCE FILES                                     
                                                                                
BPIXTAB = 'jref$25g1256nj_bpx.fits' / bad pixel table                           
CCDTAB  = 'jref$44h1714cj_ccd.fits' / CCD calibration parameters                
ATODTAB = 'N/A                    ' / analog to digital correction file         
OSCNTAB = 'jref$17717071j_osc.fits' / CCD overscan table                        
BIASFILE= 'jref$25e1534mj_bia.fits' / bias image file name                      
FLSHFILE= 'N/A                    ' / post flash correction file name           
CRREJTAB= 'N/A                    ' / cosmic ray rejection parameters           
SHADFILE= 'N/A                    ' / shutter shading correction file           
DARKFILE= 'jref$4b70022fj_drk.fits' / dark image file name                      
DFLTFILE= 'N/A                    ' / delta flat field file name                
LFLTFILE= 'N/A                    ' / low order flat                            
PHOTTAB = 'N/A                    ' / Photometric throughput table              
GRAPHTAB= 'N/A                    ' / the HST graph table                       
COMPTAB = 'N/A                    ' / the HST components table                  
IDCTAB  = 'jref$4bb1536cj_idc.fits' / image distortion correction table         
DGEOFILE= 'jref$qbu16424j_dxy.fits' / Distortion correction image               
MDRIZTAB= 'jref$37g1550cj_mdz.fits' / MultiDrizzle parameter table              
CFLTFILE= 'N/A                    ' / Coronagraphic spot image                  
SPOTTAB = 'N/A                    ' / Coronagraphic spot offset table           
IMPHTTAB= 'jref$4af1559ij_imp.fits' / Image Photometry Table                    
SNKCFILE= 'jref$25e1528hj_snk.fits' / Map of sink pixels                        
SATUFILE= 'jref$5331917aj_sat.fits' / CCD pixel saturation onset map            
                                                                                
              / COSMIC RAY REJECTION ALGORITHM PARAMETERS                       
                                                                                
MEANEXP =             0.000000 / reference exposure time for parameters         
SCALENSE=             0.000000 / multiplicative scale factor applied to noise   
SKYSUB  = '    '               / sky value subtracted (MODE or NONE)            
SKYSUM  =                  0.0 / sky level from the sum of all constituent image
CRRADIUS=             0.000000 / rejection propagation radius (pixels)          
CRTHRESH=             0.000000 / rejection propagation threshold                
BADINPDQ=                    0 / data quality flag bits to reject               
REJ_RATE=                  0.0 / rate at which pixels are affected by cosmic ray
CRMASK  =                    F / flag CR-rejected pixels in input files (T/F)   
                                                                                
              / OTFR KEYWORDS                                                   
                                                                                
                                                                                
              / PATTERN KEYWORDS                                                
                                                                                
PATTERN1= 'NONE                    ' / primary pattern type                     
P1_SHAPE= '                  ' / primary pattern shape                          
P1_PURPS= '          '         / primary pattern purpose                        
P1_NPTS =                    0 / number of points in primary pattern            
P1_PSPAC=             0.000000 / point spacing for primary pattern (arc-sec)    
P1_LSPAC=             0.000000 / line spacing for primary pattern (arc-sec)     
P1_ANGLE=             0.000000 / angle between sides of parallelogram patt (deg)
P1_FRAME= '         '          / coordinate frame of primary pattern            
P1_ORINT=             0.000000 / orientation of pattern to coordinate frame (deg
P1_CENTR= '   '                / center pattern relative to pointing (yes/no)   
PATTSTEP=                    0 / position number of this point in the pattern   
                                                                                
              / POST FLASH  PARAMETERS                                          
                                                                                
FLASHDUR=                  0.0 / Exposure time in seconds: 0.1 to 409.5         
FLASHCUR= 'OFF '               / Post flash current: OFF, LOW, MED, HIGH        
FLASHSTA= 'NOT PERFORMED   '   / Status: SUCCESSFUL, ABORTED, NOT PERFORMED     
SHUTRPOS= 'MULTIPLE'           / Shutter position: A or B                       
NSHUTOPN=                    1 / Number of times shutter opened                 
                                                                                
              / ENGINEERING PARAMETERS                                          
                                                                                
CCDGAIN =                  2.0 / commanded gain of CCD                          
CCDOFSTA=                    1 / commanded CCD bias offset for amplifier A      
CCDOFSTB=                    1 / commanded CCD bias offset for amplifier B      
CCDOFSTC=                    1 / commanded CCD bias offset for amplifier C      
CCDOFSTD=                    1 / commanded CCD bias offset for amplifier D      
                                                                                
              / CALIBRATED ENGINEERING PARAMETERS                               
                                                                                
ATODGNA =        2.0200000E+00 / calibrated gain for amplifier A                
ATODGNB =        1.8860000E+00 / calibrated gain for amplifier B                
ATODGNC =        2.0170000E+00 / calibrated gain for amplifier C                
ATODGND =        2.0109999E+00 / calibrated gain for amplifier D                
READNSEA=        4.3499999E+00 / calibrated read noise for amplifier A          
READNSEB=        3.7500000E+00 / calibrated read noise for amplifier B          
READNSEC=        4.0500002E+00 / calibrated read noise for amplifier C          
READNSED=        5.0500002E+00 / calibrated read noise for amplifier D          
                                                                                
              / ASSOCIATION KEYWORDS                                            
                                                                                
CRDS_CTX= 'hst_0972.pmap'                                                       
CRDS_VER= '11.4.3, b11.4.0, 64d96076d89b32a5687a6b77bb910ab93b3a99b3'           
UPWCSVER= '1.7.2   '           / Version of STWCS used to update the WCS        
PYWCSVER= '4.3.1   '           / Version of Astropy used to update the WCS      
HISTORY CCD parameters table:                                                   
HISTORY   reference table jref$44h1714cj_ccd.fits                               
HISTORY     inflight                                                            
HISTORY     July 2009                                                           
HISTORY DQICORR complete ...                                                    
HISTORY   values checked for saturation                                         
HISTORY   DQ array initialized ...                                              
HISTORY   reference table jref$25g1256nj_bpx.fits                               
HISTORY BIASCORR complete ...                                                   
HISTORY   reference image jref$25e1534mj_bia.fits                               
HISTORY     INFLIGHT 13/01/2016 10/02/2016                                      
HISTORY     Standard full-frame bias for data taken after Jan 13 2016 01:33:37- 
HISTORY DESTRIPE: number of rows fixed per amp: 2047                            
HISTORY DESTRIPE: number of rows skipped per amp: 21                            
HISTORY BLEVCORR complete; bias level from overscan was subtracted.             
HISTORY BLEVCORR does not include correction for drift along lines.             
HISTORY   Overscan region table:                                                
HISTORY   reference table jref$17717071j_osc.fits                               
HISTORY Uncertainty array initialized.                                          
HISTORY SINKCORR complete ...                                                   
HISTORY   reference image jref$25e1528hj_snk.fits                               
HISTORY     INFLIGHT 13/01/2016 10/02/2016                                      
HISTORY     Sink pixel reference file ----------------------------              
HISTORY CCD parameters table:                                                   
HISTORY   reference table jref$44h1714cj_ccd.fits                               
HISTORY     inflight                                                            
HISTORY     July 2009                                                           
HISTORY CTE_NAME PixelCTE 2017 CTE algorithm name                               
HISTORY CTE_VER 2.0 CTE algorithm version                                       
HISTORY CTEDATE0   5.233486000000E+04 Date of instrument installation           
HISTORY PCTETRSH  -1.000000000000E+01 CTE over subtraction threshold            
HISTORY CTEDATE1   5.771044601020E+04 Date of CTE model pinning                 
HISTORY PCTEFRAC   9.445563835308E-01 CTE scaling factor                        
HISTORY PCTETLEN           60 max length of CTE trail                           
HISTORY PCTENFOR            5 Number of iter in forward model                   
HISTORY PCTENPAR            7 Number of iter in parallel transfer               
HISTORY FIXROCR            1 fix readout cosmic rays                            
HISTORY PCTECORR complete ...                                                   
HISTORY PCTERNOI  4.3499999E+00 Amp 'A' read noise clip limit (from CCDTAB).    
HISTORY PCTERNOI  3.7500000E+00 Amp 'B' read noise clip limit (from CCDTAB).    
HISTORY PCTERNOI  4.0500002E+00 Amp 'C' read noise clip limit (from CCDTAB).    
HISTORY PCTERNOI  5.0500002E+00 Amp 'D' read noise clip limit (from CCDTAB).    
HISTORY CTE parameters table:                                                   
HISTORY   reference table jref$19i16323j_cte.fits                               
DISTNAME= 'jcsz32dcq_4bb1536cj-4bb1536ej-4bb15371j'                             
SIPNAME = 'jcsz32dcq_4bb1536cj'                                                 
RULESVER=                  1.1 / Version ID for header kw rules file            
BLENDVER= '1.2.0   '           / Version of blendheader software used           
RULEFILE= '/opt/conda/lib/python3.8/site-packages/fitsblender/acs_header.rules' 
NEXTEND =                    4                                                  
FILENAME= 'jcsz32010_drc.fits'                                                  
PROD_VER= 'DrizzlePac 3.3.1'                                                    
DRIZPARS= 'jcsz32010.tra'      / Logfile for processing                         
ROOTNAME= 'jcsz32010_drc.fits'                                                  
ASN_MTYP= 'PROD-DTH'                                                            
NDRIZIM =                    8 / Drizzle, No. images drizzled onto output       
D001VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D001GEOM= 'wcs     '           / Drizzle, source of geometric information       
D001DATA= 'jcsz32dcq_flc.fits[sci,1]' / Drizzle, input data image               
D001DEXP=               1225.0 / Drizzle, input image exposure time (s)         
D001OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D001OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D001OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D001MASK= 'jcsz32dcq_sci1_final_mask.fits' / Drizzle, input weighting image     
D001WTSC=                    1 / Drizzle, weighting factor for input image      
D001KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D001PIXF=                  1.0 / Drizzle, linear size of drop                   
D001COEF= 'SIP     '           / Drizzle, source of coefficients                
D001OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D001FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D001WKEY= '' / Input image WCS Version used                                     
D001SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D001ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
D002VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D002GEOM= 'wcs     '           / Drizzle, source of geometric information       
D002DATA= 'jcsz32dcq_flc.fits[sci,2]' / Drizzle, input data image               
D002DEXP=               1225.0 / Drizzle, input image exposure time (s)         
D002OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D002OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D002OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D002MASK= 'jcsz32dcq_sci2_final_mask.fits' / Drizzle, input weighting image     
D002WTSC=                    1 / Drizzle, weighting factor for input image      
D002KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D002PIXF=                  1.0 / Drizzle, linear size of drop                   
D002COEF= 'SIP     '           / Drizzle, source of coefficients                
D002OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D002FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D002WKEY= '' / Input image WCS Version used                                     
D002SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D002ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
D003VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D003GEOM= 'wcs     '           / Drizzle, source of geometric information       
D003DATA= 'jcsz32deq_flc.fits[sci,1]' / Drizzle, input data image               
D003DEXP=               1307.0 / Drizzle, input image exposure time (s)         
D003OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D003OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D003OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D003MASK= 'jcsz32deq_sci1_final_mask.fits' / Drizzle, input weighting image     
D003WTSC=                    1 / Drizzle, weighting factor for input image      
D003KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D003PIXF=                  1.0 / Drizzle, linear size of drop                   
D003COEF= 'SIP     '           / Drizzle, source of coefficients                
D003OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D003FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D003WKEY= '' / Input image WCS Version used                                     
D003SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D003ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
D004VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D004GEOM= 'wcs     '           / Drizzle, source of geometric information       
D004DATA= 'jcsz32deq_flc.fits[sci,2]' / Drizzle, input data image               
D004DEXP=               1307.0 / Drizzle, input image exposure time (s)         
D004OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D004OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D004OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D004MASK= 'jcsz32deq_sci2_final_mask.fits' / Drizzle, input weighting image     
D004WTSC=                    1 / Drizzle, weighting factor for input image      
D004KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D004PIXF=                  1.0 / Drizzle, linear size of drop                   
D004COEF= 'SIP     '           / Drizzle, source of coefficients                
D004OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D004FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D004WKEY= '' / Input image WCS Version used                                     
D004SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D004ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
D005VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D005GEOM= 'wcs     '           / Drizzle, source of geometric information       
D005DATA= 'jcsz32diq_flc.fits[sci,1]' / Drizzle, input data image               
D005DEXP=               1307.0 / Drizzle, input image exposure time (s)         
D005OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D005OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D005OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D005MASK= 'jcsz32diq_sci1_final_mask.fits' / Drizzle, input weighting image     
D005WTSC=                    1 / Drizzle, weighting factor for input image      
D005KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D005PIXF=                  1.0 / Drizzle, linear size of drop                   
D005COEF= 'SIP     '           / Drizzle, source of coefficients                
D005OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D005FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D005WKEY= '' / Input image WCS Version used                                     
D005SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D005ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
D006VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D006GEOM= 'wcs     '           / Drizzle, source of geometric information       
D006DATA= 'jcsz32diq_flc.fits[sci,2]' / Drizzle, input data image               
D006DEXP=               1307.0 / Drizzle, input image exposure time (s)         
D006OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D006OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D006OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D006MASK= 'jcsz32diq_sci2_final_mask.fits' / Drizzle, input weighting image     
D006WTSC=                    1 / Drizzle, weighting factor for input image      
D006KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D006PIXF=                  1.0 / Drizzle, linear size of drop                   
D006COEF= 'SIP     '           / Drizzle, source of coefficients                
D006OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D006FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D006WKEY= '' / Input image WCS Version used                                     
D006SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D006ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
D007VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D007GEOM= 'wcs     '           / Drizzle, source of geometric information       
D007DATA= 'jcsz32dlq_flc.fits[sci,1]' / Drizzle, input data image               
D007DEXP=               1307.0 / Drizzle, input image exposure time (s)         
D007OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D007OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D007OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D007MASK= 'jcsz32dlq_sci1_final_mask.fits' / Drizzle, input weighting image     
D007WTSC=                    1 / Drizzle, weighting factor for input image      
D007KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D007PIXF=                  1.0 / Drizzle, linear size of drop                   
D007COEF= 'SIP     '           / Drizzle, source of coefficients                
D007OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D007FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D007WKEY= '' / Input image WCS Version used                                     
D007SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D007ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
D008VER = 'Callable C-based DRIZZLE Version 0.8 (20th May 2009)' / Drizzle, task
D008GEOM= 'wcs     '           / Drizzle, source of geometric information       
D008DATA= 'jcsz32dlq_flc.fits[sci,2]' / Drizzle, input data image               
D008DEXP=               1307.0 / Drizzle, input image exposure time (s)         
D008OUDA= 'jcsz32010_drc.fits' / Drizzle, output data image                     
D008OUWE= 'jcsz32010_drc_wht.fits' / Drizzle, output weighting image            
D008OUCO= 'jcsz32010_drc_ctx.fits' / Drizzle, output context image              
D008MASK= 'jcsz32dlq_sci2_final_mask.fits' / Drizzle, input weighting image     
D008WTSC=                    1 / Drizzle, weighting factor for input image      
D008KERN= 'square  '           / Drizzle, form of weight distribution kernel    
D008PIXF=                  1.0 / Drizzle, linear size of drop                   
D008COEF= 'SIP     '           / Drizzle, source of coefficients                
D008OUUN= 'cps     '           / Drizzle, units of output image - counts or cps 
D008FVAL= 'INDEF   '           / Drizzle, fill value for zero weight output pix 
D008WKEY= '' / Input image WCS Version used                                     
D008SCAL=                 0.05 / Drizzle, pixel size (arcsec) of output image   
D008ISCL=                 0.05 / Drizzle, default IDCTAB pixel size(arcsec)     
HISTORY CCD parameters table:                                                   
HISTORY   reference table jref$44h1714cj_ccd.fits                               
HISTORY     inflight                                                            
HISTORY     July 2009                                                           
HISTORY DARKCORR complete ...                                                   
HISTORY   reference image jref$4b70021pj_dkc.fits                               
HISTORY     INFLIGHT 13/01/2016 10/02/2016                                      
HISTORY     CTE corrected dark for WFC data taken after Jan 13 2016 01:33:37--- 
HISTORY FLATCORR complete ...                                                   
HISTORY   reference image jref$qb12257sj_pfl.fits                               
HISTORY     INFLIGHT 18/04/2002 - 04/07/2006                                    
HISTORY     F606W step +1 flat w/ mote shifted to -1 step                       
HISTORY PHOTCORR complete ...                                                   
HISTORY   reference table jref$4af1559ij_imp.fits                               
HISTORY EXPSCORR complete ...                                                   
HISTORY ============================================================            
HISTORY Header Generation rules:                                                
HISTORY     Rules used to combine headers of input files                        
HISTORY     Start of rules...                                                   
HISTORY ------------------------------------------------------------            
HISTORY !VERSION = 1.1                                                          
HISTORY !INSTRUMENT = ACS                                                       
HISTORY ROOTNAME                                                                
HISTORY EXTNAME                                                                 
HISTORY EXTVER                                                                  
HISTORY A_0_2                                                                   
HISTORY A_0_3                                                                   
HISTORY A_0_4                                                                   
HISTORY A_1_1                                                                   
HISTORY A_1_2                                                                   
HISTORY A_1_3                                                                   
HISTORY A_2_0                                                                   
HISTORY A_2_1                                                                   
HISTORY A_2_2                                                                   
HISTORY A_3_0                                                                   
HISTORY A_3_1                                                                   
HISTORY A_4_0                                                                   
HISTORY ACQNAME                                                                 
HISTORY A_ORDER                                                                 
HISTORY APERTURE                                                                
HISTORY ASN_ID                                                                  
HISTORY ASN_MTYP                                                                
HISTORY ASN_TAB                                                                 
HISTORY ATODCORR                                                                
HISTORY ATODGNA                                                                 
HISTORY ATODGNB                                                                 
HISTORY ATODGNC                                                                 
HISTORY ATODGND                                                                 
HISTORY ATODTAB                                                                 
HISTORY B_0_2                                                                   
HISTORY B_0_3                                                                   
HISTORY B_0_4                                                                   
HISTORY B_1_1                                                                   
HISTORY B_1_2                                                                   
HISTORY B_1_3                                                                   
HISTORY B_2_0                                                                   
HISTORY B_2_1                                                                   
HISTORY B_2_2                                                                   
HISTORY B_3_0                                                                   
HISTORY B_3_1                                                                   
HISTORY B_4_0                                                                   
HISTORY BADINPDQ                                                                
HISTORY BIASCORR                                                                
HISTORY BIASFILE                                                                
HISTORY BIASLEVA                                                                
HISTORY BIASLEVB                                                                
HISTORY BIASLEVC                                                                
HISTORY BIASLEVD                                                                
HISTORY BINAXIS1                                                                
HISTORY BINAXIS2                                                                
HISTORY BITPIX                                                                  
HISTORY BLEVCORR                                                                
HISTORY B_ORDER                                                                 
HISTORY BPIXTAB                                                                 
HISTORY BUNIT                                                                   
HISTORY CAL_VER                                                                 
HISTORY CBLKSIZ                                                                 
HISTORY CCDAMP                                                                  
HISTORY CCDCHIP                                                                 
HISTORY CCDGAIN                                                                 
HISTORY CCDOFSTA                                                                
HISTORY CCDOFSTB                                                                
HISTORY CCDOFSTC                                                                
HISTORY CCDOFSTD                                                                
HISTORY CCDTAB                                                                  
HISTORY CD1_1                                                                   
HISTORY CD1_2                                                                   
HISTORY CD2_1                                                                   
HISTORY CD2_2                                                                   
HISTORY CENTERA1                                                                
HISTORY CENTERA2                                                                
HISTORY CFLTFILE                                                                
HISTORY COMPTAB                                                                 
HISTORY COMPTYP                                                                 
HISTORY CRCORR                                                                  
HISTORY CRMASK                                                                  
HISTORY CRPIX1                                                                  
HISTORY CRPIX2                                                                  
HISTORY CRRADIUS                                                                
HISTORY CRREJTAB                                                                
HISTORY CRSIGMAS                                                                
HISTORY CRSPLIT                                                                 
HISTORY CRTHRESH                                                                
HISTORY CRVAL1                                                                  
HISTORY CRVAL2                                                                  
HISTORY CTE_NAME                                                                
HISTORY CTE_VER                                                                 
HISTORY CTEDIR                                                                  
HISTORY CTEIMAGE                                                                
HISTORY CTYPE1                                                                  
HISTORY CTYPE2                                                                  
HISTORY D2IMFILE                                                                
HISTORY DARKCORR                                                                
HISTORY DARKFILE                                                                
HISTORY DATE                                                                    
HISTORY DATE-OBS                                                                
HISTORY DEC_APER                                                                
HISTORY DEC_TARG                                                                
HISTORY DETECTOR                                                                
HISTORY DFLTFILE                                                                
HISTORY DGEOFILE                                                                
HISTORY DIRIMAGE                                                                
HISTORY DQICORR                                                                 
HISTORY DRIZCORR                                                                
HISTORY DRKCFILE                                                                
HISTORY EQUINOX                                                                 
HISTORY ERRCNT                                                                  
HISTORY EXPEND                                                                  
HISTORY EXPFLAG                                                                 
HISTORY EXPNAME                                                                 
HISTORY EXPSCORR                                                                
HISTORY EXPSTART                                                                
HISTORY EXPTIME                                                                 
HISTORY EXTEND                                                                  
HISTORY FGSLOCK                                                                 
HISTORY FILENAME                                                                
HISTORY FILETYPE                                                                
HISTORY FILLCNT                                                                 
HISTORY FILTER1                                                                 
HISTORY FILTER2                                                                 
HISTORY FLASHCUR                                                                
HISTORY FLASHDUR                                                                
HISTORY FLASHSTA                                                                
HISTORY FLATCORR                                                                
HISTORY FLSHCORR                                                                
HISTORY FLSHFILE                                                                
HISTORY FW1ERROR                                                                
HISTORY FW1OFFST                                                                
HISTORY FW2ERROR                                                                
HISTORY FW2OFFST                                                                
HISTORY FWSERROR                                                                
HISTORY FWSOFFST                                                                
HISTORY GCOUNT                                                                  
HISTORY GLINCORR                                                                
HISTORY GLOBLIM                                                                 
HISTORY GLOBRATE                                                                
HISTORY GOODMAX                                                                 
HISTORY GOODMEAN                                                                
HISTORY GOODMIN                                                                 
HISTORY GRAPHTAB                                                                
HISTORY GYROMODE                                                                
HISTORY IDCSCALE                                                                
HISTORY IDCTAB                                                                  
HISTORY IDCTHETA                                                                
HISTORY IDCV2REF                                                                
HISTORY IDCV3REF                                                                
HISTORY IMAGETYP                                                                
HISTORY IMPHTTAB                                                                
HISTORY INHERIT                                                                 
HISTORY INITGUES                                                                
HISTORY INSTRUME                                                                
HISTORY JWROTYPE                                                                
HISTORY LFLGCORR                                                                
HISTORY LFLTFILE                                                                
HISTORY LINENUM                                                                 
HISTORY LOSTPIX                                                                 
HISTORY LRC_FAIL                                                                
HISTORY LRC_XSTS                                                                
HISTORY LRFWAVE                                                                 
HISTORY LTM1_1                                                                  
HISTORY LTM2_2                                                                  
HISTORY LTV1                                                                    
HISTORY LTV2                                                                    
HISTORY MDECODT1                                                                
HISTORY MDECODT2                                                                
HISTORY MDRIZSKY                                                                
HISTORY MDRIZTAB                                                                
HISTORY MEANBLEV                                                                
HISTORY MEANDARK                                                                
HISTORY MEANEXP                                                                 
HISTORY MEANFLSH                                                                
HISTORY MLINTAB                                                                 
HISTORY MOFFSET1                                                                
HISTORY MOFFSET2                                                                
HISTORY MOONANGL                                                                
HISTORY MTFLAG                                                                  
HISTORY NAXIS                                                                   
HISTORY NAXIS1                                                                  
HISTORY NAXIS2                                                                  
HISTORY NCOMBINE                                                                
HISTORY NEXTEND                                                                 
HISTORY NGOODPIX                                                                
HISTORY NPOLFILE                                                                
HISTORY NRPTEXP                                                                 
HISTORY OBSMODE                                                                 
HISTORY OBSTYPE                                                                 
HISTORY OCD1_1                                                                  
HISTORY OCD1_2                                                                  
HISTORY OCD2_1                                                                  
HISTORY OCD2_2                                                                  
HISTORY OCRPIX1                                                                 
HISTORY OCRPIX2                                                                 
HISTORY OCRVAL1                                                                 
HISTORY OCRVAL2                                                                 
HISTORY OCTYPE1                                                                 
HISTORY OCTYPE2                                                                 
HISTORY OCX10                                                                   
HISTORY OCX11                                                                   
HISTORY OCY10                                                                   
HISTORY OCY11                                                                   
HISTORY ONAXIS1                                                                 
HISTORY ONAXIS2                                                                 
HISTORY OORIENTA                                                                
HISTORY OPUS_VER                                                                
HISTORY ORIENTAT                                                                
HISTORY ORIGIN                                                                  
HISTORY OSCNTAB                                                                 
HISTORY P1_ANGLE                                                                
HISTORY P1_CENTR                                                                
HISTORY P1_FRAME                                                                
HISTORY P1_LSPAC                                                                
HISTORY P1_NPTS                                                                 
HISTORY P1_ORINT                                                                
HISTORY P1_PSPAC                                                                
HISTORY P1_PURPS                                                                
HISTORY P1_SHAPE                                                                
HISTORY PA_APER                                                                 
HISTORY PATTERN1                                                                
HISTORY PATTSTEP                                                                
HISTORY PA_V3                                                                   
HISTORY PCOUNT                                                                  
HISTORY PCTECORR                                                                
HISTORY PCTEFRAC                                                                
HISTORY PCTENSMD                                                                
HISTORY PCTERNCL                                                                
HISTORY PCTESHFT                                                                
HISTORY PCTESMIT                                                                
HISTORY PCTETAB                                                                 
HISTORY PFLTFILE                                                                
HISTORY PHOTBW                                                                  
HISTORY PHOTCORR                                                                
HISTORY PHOTFLAM                                                                
HISTORY PHOTMODE                                                                
HISTORY PHOTPLAM                                                                
HISTORY PHOTTAB                                                                 
HISTORY PHOTZPT                                                                 
HISTORY PODPSFF                                                                 
HISTORY POSTARG1                                                                
HISTORY POSTARG2                                                                
HISTORY PRIMESI                                                                 
HISTORY PR_INV_F                                                                
HISTORY PR_INV_L                                                                
HISTORY PR_INV_M                                                                
HISTORY PROCTIME                                                                
HISTORY PROPAPER                                                                
HISTORY PROPOSID                                                                
HISTORY QUALCOM1                                                                
HISTORY QUALCOM2                                                                
HISTORY QUALCOM3                                                                
HISTORY QUALITY                                                                 
HISTORY RA_APER                                                                 
HISTORY RA_TARG                                                                 
HISTORY READNSEA                                                                
HISTORY READNSEB                                                                
HISTORY READNSEC                                                                
HISTORY READNSED                                                                
HISTORY REFFRAME                                                                
HISTORY REJ_RATE                                                                
HISTORY RPTCORR                                                                 
HISTORY SCALENSE                                                                
HISTORY SCLAMP                                                                  
HISTORY SDQFLAGS                                                                
HISTORY SHADCORR                                                                
HISTORY SHADFILE                                                                
HISTORY SHUTRPOS                                                                
HISTORY SIMPLE                                                                  
HISTORY SIZAXIS1                                                                
HISTORY SIZAXIS2                                                                
HISTORY SKYSUB                                                                  
HISTORY SKYSUM                                                                  
HISTORY SNRMAX                                                                  
HISTORY SNRMEAN                                                                 
HISTORY SNRMIN                                                                  
HISTORY SOFTERRS                                                                
HISTORY SPOTTAB                                                                 
HISTORY STATFLAG                                                                
HISTORY STDCFFF                                                                 
HISTORY STDCFFP                                                                 
HISTORY SUBARRAY                                                                
HISTORY SUN_ALT                                                                 
HISTORY SUNANGLE                                                                
HISTORY TARGNAME                                                                
HISTORY TDDALPHA                                                                
HISTORY TDDBETA                                                                 
HISTORY TELESCOP                                                                
HISTORY TIME-OBS                                                                
HISTORY T_SGSTAR                                                                
HISTORY VAFACTOR                                                                
HISTORY WCSAXES                                                                 
HISTORY WCSCDATE                                                                
HISTORY WFCMPRSD                                                                
HISTORY WCSNAME                                                                 
HISTORY WRTERR                                                                  
HISTORY XTENSION                                                                
HISTORY WCSNAMEO                                                                
HISTORY WCSAXESO                                                                
HISTORY LONPOLEO                                                                
HISTORY LATPOLEO                                                                
HISTORY RESTFRQO                                                                
HISTORY RESTWAVO                                                                
HISTORY CD1_1O                                                                  
HISTORY CD1_2O                                                                  
HISTORY CD2_1O                                                                  
HISTORY CD2_2O                                                                  
HISTORY CDELT1O                                                                 
HISTORY CDELT2O                                                                 
HISTORY CRPIX1O                                                                 
HISTORY CRPIX2O                                                                 
HISTORY CRVAL1O                                                                 
HISTORY CRVAL2O                                                                 
HISTORY CTYPE1O                                                                 
HISTORY CTYPE2O                                                                 
HISTORY CUNIT1O                                                                 
HISTORY CUNIT2O                                                                 
HISTORY APERTURE  APERTURE  multi                                               
HISTORY DETECTOR  DETECTOR  first                                               
HISTORY EXPEND    EXPEND    max                                                 
HISTORY EXPSTART  EXPSTART  min                                                 
HISTORY EXPTIME   TEXPTIME  sum                                                 
HISTORY EXPTIME   EXPTIME   sum                                                 
HISTORY FILTER1   FILTER1   multi                                               
HISTORY FILTER2   FILTER2   multi                                               
HISTORY GOODMAX   GOODMAX   max                                                 
HISTORY GOODMEAN  GOODMEAN  mean                                                
HISTORY GOODMIN   GOODMIN   min                                                 
HISTORY INHERIT   INHERIT   first # maintain IRAF compatibility                 
HISTORY INSTRUME  INSTRUME  first                                               
HISTORY LRFWAVE   LRFWAVE   first                                               
HISTORY NCOMBINE  NCOMBINE  sum                                                 
HISTORY MDRIZSKY  MDRIZSKY  mean                                                
HISTORY PHOTBW    PHOTBW    mean                                                
HISTORY PHOTFLAM  PHOTFLAM  mean                                                
HISTORY PHOTMODE  PHOTMODE  first                                               
HISTORY PHOTPLAM  PHOTPLAM  mean                                                
HISTORY PHOTZPT   PHOTZPT   mean                                                
HISTORY PROPOSID  PROPOSID  first                                               
HISTORY SNRMAX    SNRMAX    max                                                 
HISTORY SNRMEAN   SNRMEAN   mean                                                
HISTORY SNRMIN    SNRMIN    min                                                 
HISTORY TARGNAME  TARGNAME  first                                               
HISTORY TELESCOP  TELESCOP  first                                               
HISTORY WCSNAME   WCSNAME   first                                               
HISTORY ATODCORR  ATODCORR  multi                                               
HISTORY ATODGNA   ATODGNA   first                                               
HISTORY ATODGNB   ATODGNB   first                                               
HISTORY ATODGNC   ATODGNC   first                                               
HISTORY ATODGND   ATODGND   first                                               
HISTORY ATODTAB   ATODTAB   multi                                               
HISTORY BADINPDQ  BADINPDQ  sum                                                 
HISTORY BIASCORR  BIASCORR  multi                                               
HISTORY BIASFILE  BIASFILE  multi                                               
HISTORY BLEVCORR  BLEVCORR  multi                                               
HISTORY BPIXTAB   BPIXTAB   multi                                               
HISTORY CCDCHIP   CCDCHIP   first                                               
HISTORY CCDGAIN   CCDGAIN   first                                               
HISTORY CCDOFSTA  CCDOFSTA  first                                               
HISTORY CCDOFSTB  CCDOFSTB  first                                               
HISTORY CCDOFSTC  CCDOFSTC  first                                               
HISTORY CCDOFSTD  CCDOFSTD  first                                               
HISTORY CCDTAB      CCDTAB    multi                                             
HISTORY CFLTFILE  CFLTFILE  multi                                               
HISTORY COMPTAB   COMPTAB   multi                                               
HISTORY CRCORR      CRCORR    multi                                             
HISTORY CRMASK      CRMASK    first                                             
HISTORY CRRADIUS  CRRADIUS  first                                               
HISTORY CRREJTAB  CRREJTAB  multi                                               
HISTORY CRSPLIT   CRSPLIT   first                                               
HISTORY CRTHRESH  CRTHRESH  first                                               
HISTORY CTEDIR      CTEDIR    multi                                             
HISTORY CTEIMAGE  CTEIMAGE  first                                               
HISTORY DARKCORR  DARKCORR  multi                                               
HISTORY DARKFILE  DARKFILE  multi                                               
HISTORY DATE-OBS  DATE-OBS  first                                               
HISTORY DEC_APER  DEC_APER  first                                               
HISTORY DFLTFILE  DFLTFILE  multi                                               
HISTORY DGEOFILE  DGEOFILE  multi                                               
HISTORY DIRIMAGE  DIRIMAGE  multi                                               
HISTORY DQICORR   DQICORR   multi                                               
HISTORY DRIZCORR  DRIZCORR  multi                                               
HISTORY EXPFLAG   EXPFLAG   multi                                               
HISTORY EXPSCORR  EXPSCORR  multi                                               
HISTORY FGSLOCK   FGSLOCK   multi                                               
HISTORY FLASHCUR  FLASHCUR  multi                                               
HISTORY FLASHDUR  FLASHDUR  first                                               
HISTORY FLASHSTA  FLASHSTA  first                                               
HISTORY FLATCORR  FLATCORR  multi                                               
HISTORY FLSHCORR  FLSHCORR  multi                                               
HISTORY FLSHFILE  FLSHFILE  multi                                               
HISTORY FW1ERROR  FW1ERROR  multi                                               
HISTORY FW1OFFST  FW1OFFST  first                                               
HISTORY FW2ERROR  FW2ERROR  multi                                               
HISTORY FW2OFFST  FW2OFFST  first                                               
HISTORY FWSERROR  FWSERROR  multi                                               
HISTORY FWSOFFST  FWSOFFST  first                                               
HISTORY GRAPHTAB  GRAPHTAB  multi                                               
HISTORY GYROMODE  GYROMODE  multi                                               
HISTORY IDCTAB      IDCTAB    multi                                             
HISTORY IMAGETYP  IMAGETYP  first                                               
HISTORY IMPHTTAB  IMPHTTAB  multi                                               
HISTORY LFLGCORR  LFLGCORR  multi                                               
HISTORY LFLTFILE  LFLTFILE  multi                                               
HISTORY LTM1_1    LTM1_1    float_one                                           
HISTORY LTM2_2    LTM2_2    float_one                                           
HISTORY MDRIZTAB  MDRIZTAB  multi                                               
HISTORY MEANEXP   MEANEXP   first                                               
HISTORY MOONANGL  MOONANGL  first                                               
HISTORY NRPTEXP   NRPTEXP   first                                               
HISTORY OBSMODE   OBSMODE   multi                                               
HISTORY OBSTYPE   OBSTYPE   first                                               
HISTORY OSCNTAB   OSCNTAB   multi                                               
HISTORY P1_ANGLE  P1_ANGLE  first                                               
HISTORY P1_CENTR  P1_CENTR  multi                                               
HISTORY P1_FRAME  P1_FRAME  multi                                               
HISTORY P1_LSPAC  P1_LSPAC  first                                               
HISTORY P1_NPTS   P1_NPTS   first                                               
HISTORY P1_ORINT  P1_ORINT  first                                               
HISTORY P1_PSPAC  P1_PSPAC  first                                               
HISTORY P1_PURPS  P1_PURPS  multi                                               
HISTORY P1_SHAPE  P1_SHAPE  multi                                               
HISTORY P2_ANGLE  P2_ANGLE  first                                               
HISTORY P2_CENTR  P2_CENTR  multi                                               
HISTORY P2_FRAME  P2_FRAME  multi                                               
HISTORY P2_LSPAC  P2_LSPAC  first                                               
HISTORY P2_NPTS   P2_NPTS   first                                               
HISTORY P2_ORINT  P2_ORINT  first                                               
HISTORY P2_PSPAC  P2_PSPAC  first                                               
HISTORY P2_PURPS  P2_PURPS  multi                                               
HISTORY P2_SHAPE  P2_SHAPE  multi                                               
HISTORY PATTERN1  PATTERN1  multi                                               
HISTORY PATTERN2  PATTERN2  multi                                               
HISTORY PATTSTEP  PATTSTEP  first                                               
HISTORY PHOTCORR  PHOTCORR  multi                                               
HISTORY PHOTTAB   PHOTTAB   multi                                               
HISTORY POSTARG1  POSTARG1  first                                               
HISTORY POSTARG2  POSTARG2  first                                               
HISTORY PRIMESI   PRIMESI   multi                                               
HISTORY PROPAPER  PROPAPER  multi                                               
HISTORY RA_APER   RA_APER   first                                               
HISTORY READNSEA  READNSEA  first                                               
HISTORY READNSEB  READNSEB  first                                               
HISTORY READNSEC  READNSEC  first                                               
HISTORY READNSED  READNSED  first                                               
HISTORY REJ_RATE  REJ_RATE  first                                               
HISTORY SCALENSE  SCALENSE  first                                               
HISTORY SCLAMP      SCLAMP    multi                                             
HISTORY SHADCORR  SHADCORR  multi                                               
HISTORY SHADFILE  SHADFILE  multi                                               
HISTORY SHUTRPOS  SHUTRPOS  multi                                               
HISTORY SKYSUB      SKYSUB    multi                                             
HISTORY SKYSUM      SKYSUM    sum                                               
HISTORY SPOTTAB   SPOTTAB   multi                                               
HISTORY SUBARRAY  SUBARRAY  first                                               
HISTORY SUNANGLE  SUNANGLE  first                                               
HISTORY SUN_ALT   SUN_ALT   first                                               
HISTORY WRTERR      WRTERR    multi                                             
HISTORY ------------------------------------------------------------            
HISTORY     End of rules...                                                     
HISTORY ============================================================            
HISTORY AstroDrizzle processing performed using:                                
HISTORY     AstroDrizzle Version 3.3.1                                          
HISTORY     PyFITS Version 4.3.1                                                
HISTORY     Numpy Version 1.21.2                                                


Figure 2.2 shows the WFC apertures plotted with respect to the V2,V3 reference frame, and oriented such that the x-axis runs approximately towards the right and the y-axis runs approximately straight up. In pipeline data products, WFC2 is displayed below WFC1 (along the y-axis) and is therefore designated as extension 1.

Figure 2.2: WFC apertures Compared with the V2/V3 Reference Frame


In pipeline data products, WFC2 is displayed below WFC1 (along the y-axis) and is therefore designated as extension 1. To display the science image for WFC1, the user must specify the extension fits['SCI',2] or fits[4]. The WFC1 error and data quality arrays are specified as ['ERR',2] (or [5]) and ['DQ',2] (or [6]), respectively. The readout amplifiers (A,B,C,D) are indicated on the figure. Refer back to Figure 2.1 for the full list of extensions by detector, noting that some additional variable number of astrometric headerlet extensions may now also be present for ACS/WFC Hubble Advanced Products (HAP) images.


1 Simple Image Polynomial (SIP) convention (Shupe et. al 2005). This convention has been in use for describing the geometry of Spitzer Space Telescope images, and it has become a FITS standard. Representing image distortion corrections using the SIP convention improves the handling of image combination and astrometric information.