Instrument Science Report ACS-99-05
Design of the ACS Science Headers
Robert Jedrzejewski
25th June 1999
ABSTRACT
The decisions made in the design of the data format for ACS images are described. The
ACS file formats will use FITS with extensions, as has been introduced for STIS and NICMOS. The packaging of the data products is also described. The Science Headers are
heavily modelled on the STIS imaging headers, and prototype headers for WFC, HRC and
SBC imaging and HRC acquisitions are presented.
1. Introduction
The Advanced Camera for Surveys (ACS) inherits much of its functionality from the
STIS imaging modes. The CCDs are manufactured by SITe, and the Solar Blind Channel
(SBC) has a detector that is a flight-spare STIS FUV-MAMA. It is therefore natural to try
to model the ACS science data headers as much as possible on the STIS imaging headers,
so that much of the design is re-used.
2. The form of ACS data
ACS science data will come in three different forms:
1. Wide-Field Channel (WFC)
The WFC uses two 2048x4096 SITe CCD chips butted side-by-side to make a
4096x4096 data array. Including overscans, this appears as two 4144x2068 arrays.
2. High-Resolution Channel (HRC)
The HRC uses a 1024x1024 pixel CCD that is architecturally identical to those of the
STIS CCD channel. Including overscans, the image size is 1062x1044.
3. Solar-Blind Channel (SBC)
The SBC uses a 1024x1024 pixel MAMA that is identical to the FUV-MAMA of
STIS. However, time-tag and hi-res modes were dropped for the ACS MAMA.
1
3. Decisions about data format
File format:
Although the WFC data resembles WFPC2 in that it has independent CCD arrays, it
seems that GEIS, the prototype WF/PC and WFPC2 format, is coming to the end of its
usefulness. It was therefore decided to go with the format chosen for the newest HST
instruments; FITS with extensions. The WFC data then fits naturally in this framework, as
the data from the two chips can be packaged in separate imsets. The decision to keep the
two CCD chips as separate images, rather than to combine them into a single 4096x4096
image, was made to allow for the fact that the coefficients of the coordinate transformations between pixel and sky position will be different for each chip. It also makes the
memory requirements of any analysis task that reads the whole image into memory
somewhat less demanding if the data are handled one chip at a time.
Again, the STIS format was copied for the form of the imsets; each imset has a SCI
extension holding the science pixel data, an ERR extension that CALACS will use to populate an error array, and a DQ extension with information about data quality. For
calibrated WFC data, this would result in a large file size (4096x4096x4 bytes for science
data, 4096x4096x4 bytes for the ERR array and 4096x4096x2 bytes for the DQ array, for
a total of 160Mb), so some discussion was devoted to the possibility of storing the ERR
array in a 2 byte array (by taking the log of the ERR values and then scaling to 16-bit integers), and even discarding the ERR array, but eventually the STIS format was adopted for
the sake of consistency. It was considered undesirable to have users needing to remember
which form of the error array goes with which detector. The saving of 20% in the image
size was not considered enough of a gain to justify this somewhat confusing situation.The
prevalence of large-format detectors at many ground-based observatories has meant that
such image sizes are no longer out of the ordinary.
Packaging:
Like STIS and NICMOS, the ability to associate exposures for subsequent processing
as a grouped set was desired for the calibration of cosmic-ray split images, REPEATOBS
exposures and (in the future) dithered datasets. STIS groups the raw exposures in a product with the form of the association name with “_raw” appended, so that the individual
exposures are not initially individually packaged when sent to the proposer on tape or else
retrieved from the Hubble Data Archive. ACS WFC data already have imsets corresponding to the two CCD chips; adding another hierarchy was considered unwieldy.
The solution adopted for ACS was to mirror the NICMOS packaging. While the products made from associations will resemble the STIS association products (_crj for cosmicray split associations, _sfl for REPEATOBS associations and _dth for dithered associations) the raw data exposures will be packaged as individual _raw images, with the
2
ipppssoot name corresponding to that of the exposure. This also makes the _raw files more
manageable in size; since the pixel values are stored as 2-byte integers, the raw data files
are “only” 32Mb in size, which makes transmission via the Internet more palatable,
especially since the integer format responds well to compression.
4. Science Data Headers
Here the form of the STIS science data headers serves as a model. It is recognized that
the three detectors require slightly different structure, with the SBC MAMA headers
rather different from the WFC and HRC CCD headers. There is also a necessity for a
slightly different header for HRC ACQ exposures, since these are treated differently by
CALACS and return different information to the user.
Small changes were made to the STIS headers, mainly to reflect the emphasis on
imaging, and to introduce some items that are ACS-specific. Also, some STIS keyword
sections were just not thought to be terribly useful, and were discarded.
The major differences from the STIS headers are as follows:
1. The keywords OPT_ELEM and FILTER were changed to FILTER1 and FILTER2.
2. The READOUT DEFINITION PARAMETERS block was moved from the primary header to the SCI extension, since they can be chip-specific for WFC data.
3. The ENGINEERING PARAMETERS and CALIBRATED ENGINEERING
PARAMETERS blocks were expanded to account for the fact that all four amplifiers may be used to read out the CCDs.
4. The PHOTOMETRY KEYWORDS block was moved to the SCI extension. These
describe the sensitivity of the instrument in counts/sec/(erg/cm2/s/Å). Chip-to-chip
differences could either be incorporated into the flatfields, or else recorded in the
DQE curves in the SYNPHOT tables. The latter solution is much cleaner, as it only
requires changing a pair of tables if the sensitivity is re-calibrated; the former
method would require delivering a complete new set of flatfields. This does mean
that the photometry parameters are chip-dependent, so they must go in the SCI
extension.
5. The STIS PATTERN KEYWORDS block was renamed the PATTERN KEYWORDS block. The pattern keywords follow the design of universal pattern keywords specified in STScI OPR #38124 (http://www.sesd.stsci.edu/prsystem/cgibin/prbrowse/pr.38124)
6. The ARCHIVE SEARCH KEYWORDS block was removed. For STIS, this block
is largely used for storing spectroscopic keywords that are propagated to the science table in the Hubble Data Archive. There are no counterparts for most of these
in ACS.
3
7. The PAPER PRODUCT SUPPORT KEYWORDS block was removed. All of
these keywords are present in the spt file, and it was not considered useful to the
user to see them in the main science headers. The paper products task can access
the spt file (as it does for WFPC2 and FOC).
8. An ON-BOARD COMPRESSION INFORMATION block was added, with information about WFC compression.
9. Added 2/2/99: Added the CCDCHIP keyword to WFC headers. Added the
MEANBLEV and MEANDARK keywords to the Image Statistics and Data Quality Flags section; CALACS adds these during processing. Added a DITHCORR
flag to record processing of dithered images (projected for later in the mission).
Removed GEOCORR processing step headers, and SDISTFILE from the SBC
headers. The image distortion correction will be done offline using the IDCTAB
reference file.
The science data headers are reproduced in the following pages.
4
19.2: WFC science header
SIMPLE
BITPIX
NAXIS
EXTEND
NEXTEND
GROUPS
DATE
FILENAME
FILETYPE
=T
=
=0
=T
=
=F
=
=
=
data conform to FITS standard
bits per data value
number of data axes
File may contain standard extensions
Number of standard extensions
image is in group format
date this file was written (yyyy-mm-dd)
name of file
type of data found in data file
L1
I2
I2
L1
I2
L1
C10
C18
C03
TELESCOP
INSTRUME
EQUINOX
= HST
=
= 2000.0
telescope used to acquire data
identifier for instrument used to acquire data
equinox of celestial coord. system
C03
C06
R4
/ DATA DESCRIPTION KEYWORDS
ROOTNAME
IMAGETYP
PRIMESI
=
=
=
rootname of the observation set
type of exposure identifier
instrument designated as prime
C09
C18
C06
proposer’s target name
right ascension of the target (deg) (J2000)
declination of the target (deg) (J2000)
C30
R8
R8
/ TARGET INFORMATION
TARGNAME
RA_TARG
DEC_TARG
=
=
=
/ PROPOSAL INFORMATION
PROPOSID
LINENUM
PR_INV_L
PR_INV_F
PR_INV_M
=
=
=
=
=
PEP proposal identifier
proposal logsheet line number
last name of principal investigator
first name of principal investigator
middle name / initial of principal investigator
I4
C15
C30
C20
C20
/ EXPOSURE INFORMATION
ORIENTAT
SUNANGLE
MOONANGL
SUN_ALT
FGSLOCK
DATE-OBS
TIME-OBS
EXPSTART
EXPEND
EXPTIME
EXPFLAG
=
=
=
=
= FINE
=
=
=
=
=
= NORMAL
position angle of image y axis (deg. e of n)
angle between sun and V1 axis
angle between moon and V1 axis
altitude of the sun above Earth’s limb
commanded FGS lock
(FINE,COARSE,GYROS,UNKNOWN)
R4
R4
R4
R4
C07
UT date of start of observation (yyyy-mm-dd)
UT time of start of observation (hh:mm:ss)
exposure start time (Modified Julian Date)
exposure end time (Modified Julian Date)
exposure duration (seconds)--calculated
Exposure interruption indicator
C10
C08
R8
R8
R4
C13
/ TARGET OFFSETS (POSTARGS)
POSTARG1
POSTARG2
=
=
POSTARG in axis 1 direction
POSTARG in axis 2 direction
R4
R4
/ DIAGNOSTIC KEYWORDS
OVERFLOW
CAL_VER
=
=
Number of science data overflows
CALACS code version
/ SCIENCE INSTRUMENT CONFIGURATION
5
I2
C24
CFSTATUS
OBSTYPE
OBSMODE
SCLAMP
NRPTEXP
SUBARRAY
DETECTOR
FILTER1
FILTER2
LRFWAVE
APERTURE
PROPAPER
CRSPLIT
=
=
=
=
=
=
=
=
=
=
=
=
=
configuration status (avail.,restr.,support.)
observation type - imaging or spectroscopic
operating mode
lamp status, NONE or name of lamp which is on
number of repeat exposures in set: default 1
data from a subarray (T) or full frame (F)
detector in use: WFC, HRC or SBC
element selected from filter wheel 1
element selected from filter wheel 2
proposed linear ramp filter wavelength
aperture name
proposed aperture name
number of cosmic ray split exposures
C11
C14
C08
C09
I2
L1
C03
C18
C18
R4
C16
C16
I2
/ CALIBRATION SWITCHES: PERFORM, OMIT, COMPLETE
STATFLAG
WRTERR
DQICORR
ATODCORR
BLEVCORR
BIASCORR
CRCORR
EXPSCORR
SHADCORR
DARKCORR
FLATCORR
PHOTCORR
RPTCORR
DITHCORR
=
=T
=
=
=
=
=
=
=
=
=
=
=
= OMIT
Calculate statistics?
Write out error array extension?
data quality initialization
correct for A to D conversion errors
subtract bias level computed from overscan img
Subtract bias image
combine observations to reject cosmic rays
process individual observations after cr-reject
apply shutter shading correction
Subtract dark image
flat field data
populate photometric header keywords
add individual repeat observations
process dithered images
L1
L1
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
/ CALIBRATION REFERENCE FILES
BPIXTAB
CCDTAB
ATODTAB
OSCNTAB
BIASFILE
CRREJTAB
SHADFILE
DARKFILE
PFLTFILE
DFLTFILE
LFLTFILE
PHOTTAB
IDCTAB
DITHTAB
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
bad pixel table
CCD calibration parameters
analog to digital correction file
CCD overscan table
bias image file name
cosmic ray rejection parameters
shutter shading correction file
dark image file name
pixel to pixel flat field file name
delta flat field file name
low order flat
Photometric throughput table
image distortion correction table
dither processing reference table
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
/ COSMIC RAY REJECTION ALGORITHM PARAMETERS
MEANEXP
SCALENSE
INITGUES
SKYSUB
SKYSUM
CRSIGMAS
CRRADIUS
CRTHRESH
BADINPDQ
REJ_RATE
CRMASK
=
=
=
=
=0
=
=
=
=
=0
=
reference exposure time for parameters
multiplicative scale factor applied to noise
initial guess method (MIN or MED)
sky value subtracted (MODE or NONE)
sky level from the sum of all constituent images
statistical rejection criteria
rejection propagation radius (pixels)
rejection propagation threshold
data quality flag bits to reject
rate at which pixels are affected by cosmic rays
flag CR-rejected pixels in input files (T/F)
/ PATTERN KEYWORDS
6
R4
R4
C03
C04
R4
C15
R4
R4
I2
R4
L1
PATTERN1
P1_SHAPE
P1_PURPS
P1_NPTS
P1_PSPAC
P1_LSPAC
P1_ANGLE
P1_FRAME
P1_ORINT
P1_CENTR
= NONE
=
=
=
=
=
=
=
=
=
primary pattern type
primary pattern shape
primary pattern purpose
number of points in primary pattern
point spacing for primary pattern (arc-sec)
line spacing for primary pattern (arc-sec)
angle between sides of parallelogram patt (deg)
coordinate frame of primary pattern
orientation of pattern to coordinate frame (deg)
center pattern relative to pointing (yes/no)
C18
C18
C10
I2
R4
R4
R4
C09
R4
C03
/ ENGINEERING PARAMETERS
CCDAMP
CCDGAIN
CCDOFSTA
CCDOFSTB
CCDOFSTC
CCDOFSTD
=
=
=
=
=
=
CCD amplifier read out configuration
commanded gain of CCD
commanded CCD bias offset for amplifier A
commanded CCD bias offset for amplifier B
commanded CCD bias offset for amplifier C
commanded CCD bias offset for amplifier D
C04
I2
I4
I4
I4
I4
/ CALIBRATED ENGINEERING PARAMETERS
ATODGNA
ATODGNB
ATODGNC
ATODGND
READNSEA
READNSEB
READNSEC
READNSED
=
=
=
=
=
=
=
=
calibrated gain for CCD amplifier A
calibrated gain for CCD amplifier B
calibrated gain for CCD amplifier C
calibrated gain for CCD amplifier D
calibrated read noise for amplifier A
calibrated read noise for amplifier B
calibrated read noise for amplifier C
calibrated read noise for amplifier D
R4
R4
R4
R4
R4
R4
R4
R4
= NONE
= NONE
=
unique identifier assigned to association
name of the association table
Role of the exposure in the association
C10
C18
C12
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
= 1.0
= 32768.
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
scale factor for array value to physical value
physical value for an array value of zero
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
R8
R8
/ ASSOCIATION KEYWORDS
ASN_ID
ASN_TAB
ASN_MTYP
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
BSCALE
BZERO
/ WFC CCD CHIP IDENTIFICATION
CCDCHIP
=
CCD chip (1 or 2)
/ World Coordinate System and Related Parameters
7
I2
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
/ READOUT DEFINITION PARAMETERS
CENTERA1
CENTERA2
SIZAXIS1
SIZAXIS2
BINAXIS1
BINAXIS2
=
=
=
=
=1
=1
subarray axis1 center pt in unbinned dect. pix
subarray axis2 center pt in unbinned dect. pix
subarray axis1 size in unbinned detector pixels
subarray axis2 size in unbinned detector pixels
axis1 data bin size in unbinned detector pixels
axis2 data bin size in unbinned detector pixels
I4
I4
I4
I4
I2
I2
/ PHOTOMETRY KEYWORDS
PHOTMODE
PHOTFLAM
PHOTZPT
PHOTPLAM
PHOTBW
=
=
=
=
=
observation configuration for photometric calib
inverse sensitivity, ergs/sec/cm2/s per count/s
ST magnitude zero point
Pivot wavelength
RMS bandwidth of filter plus detector
C50
R8
R4
R4
R4
position number of this point in the pattern
I2
/ PATTERN KEYWORDS
PATTSTEP
=
/ REPEATED EXPOSURES INFO
NCOMBINE
=1
number of image sets combined during CR rejection
I2
/ DATA PACKET INFORMATION
FILLCNT
ERRCNT
PODPSFF
STDCFFF
STDCFFP
=0
=0
=F
=F
= x5569
number of segments containing fill
number of segments containing errors
podps fill present (T/F)
ST DDF fill present (T/F)
ST DDF fill pattern (hex)
I4
I4
L1
L1
C10
/ ON-BOARD COMPRESSION INFORMATION
WFCMPRSD
CBLKSIZ
LOSTPIX
=
=
=
was WFC data compressed? (T/F)
size of compression block in bytes
#pixels lost due to buffer overflow
L1
I4
I4
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
=
= 32767
=
number of good pixels
serious data quality flags
minimum value of good pixels
8
I4
I4
R4
GOODMAX
GOODMEAN
SOFTERRS
MEANBLEV
MEANDARK
=
=
=
=
=
maximum value of good pixels
mean value of good pixels
number of soft error pixels (DQF=1)
average of all bias levels subtracted
average of the dark values subtracted
R4
R4
I4
R4
R4
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
=
=
=
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
I4
I4
R4
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
GOODMAX
GOODMEAN
=
= 32767
=
=
=
number of good pixels
serious data quality flags
minimum value of good pixels
maximum value of good pixels
mean value of good pixels
I4
I4
R4
R4
R4
=
=
=2
=
extension type
bits per data value
number of data axes
length of first data axis
C08
I2
I2
I4
END
XTENSION
BITPIX
NAXIS
NAXIS1
9
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
=
=0
=1
=
=T
=
=
=
=
=
=
=
=
=
=
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
I4
I4
I4
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
END
10
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
19.3: HRC science header
SIMPLE
BITPIX
NAXIS
EXTEND
NEXTEND
GROUPS
DATE
FILENAME
FILETYPE
=T
=
=0
=T
=
=F
=
=
=
data conform to FITS standard
bits per data value
number of data axes
File may contain standard extensions
Number of standard extensions
image is in group format
date this file was written (yyyy-mm-dd)
name of file
type of data found in data file
L1
I2
I2
L1
I2
L1
C10
C18
C03
TELESCOP
INSTRUME
EQUINOX
= HST
=
= 2000.0
telescope used to acquire data
identifier for instrument used to acquire data
equinox of celestial coord. system
C03
C06
R4
/ DATA DESCRIPTION KEYWORDS
ROOTNAME
IMAGETYP
PRIMESI
=
=
=
rootname of the observation set
type of exposure identifier
instrument designated as prime
C09
C18
C06
proposer’s target name
right ascension of the target (deg) (J2000)
declination of the target (deg) (J2000)
C30
R8
R8
/ TARGET INFORMATION
TARGNAME
RA_TARG
DEC_TARG
=
=
=
/ PROPOSAL INFORMATION
PROPOSID
LINENUM
PR_INV_L
PR_INV_F
PR_INV_M
=
=
=
=
=
PEP proposal identifier
proposal logsheet line number
last name of principal investigator
first name of principal investigator
middle name / initial of principal investigator
I4
C15
C30
C20
C20
/ EXPOSURE INFORMATION
ORIENTAT
SUNANGLE
MOONANGL
SUN_ALT
FGSLOCK
DATE-OBS
TIME-OBS
EXPSTART
EXPEND
EXPTIME
EXPFLAG
=
=
=
=
= FINE
=
=
=
=
=
= NORMAL
position angle of image y axis (deg. e of n)
angle between sun and V1 axis
angle between moon and V1 axis
altitude of the sun above Earth’s limb
commanded FGS lock
(FINE,COARSE,GYROS,UNKNOWN)
R4
R4
R4
R4
C07
UT date of start of observation (yyyy-mm-dd)
UT time of start of observation (hh:mm:ss)
exposure start time (Modified Julian Date)
exposure end time (Modified Julian Date)
exposure duration (seconds)--calculated
Exposure interruption indicator
C10
C08
R8
R8
R4
C13
/ TARGET OFFSETS (POSTARGS)
POSTARG1
POSTARG2
=
=
POSTARG in axis 1 direction
POSTARG in axis 2 direction
R4
R4
/ DIAGNOSTIC KEYWORDS
OVERFLOW
CAL_VER
=
=
Number of science data overflows
CALACS code version
/ SCIENCE INSTRUMENT CONFIGURATION
11
I2
C24
CFSTATUS
OBSTYPE
OBSMODE
SCLAMP
NRPTEXP
SUBARRAY
DETECTOR
FILTER1
FILTER2
LRFWAVE
APERTURE
PROPAPER
CRSPLIT
=
=
=
=
=
=
=
=
=
=
=
=
=
configuration status (avail.,restr.,support.)
observation type - imaging or spectroscopic
operating mode
lamp status, NONE or name of lamp which is on
number of repeat exposures in set: default 1
data from a subarray (T) or full frame (F)
detector in use: WFC, HRC or SBC
element selected from filter wheel 1
element selected from filter wheel 2
proposed linear ramp filter wavelength
aperture name
proposed aperture name
number of cosmic ray split exposures
C11
C14
C08
C09
I2
L1
C03
C18
C18
R4
C16
C16
I2
/ CALIBRATION SWITCHES: PERFORM, OMIT, COMPLETE
STATFLAG
WRTERR
DQICORR
ATODCORR
BLEVCORR
BIASCORR
CRCORR
EXPSCORR
SHADCORR
DARKCORR
FLATCORR
PHOTCORR
RPTCORR
DITHCORR
=
=T
=
=
=
=
=
=
=
=
=
=
=
= OMIT
Calculate statistics?
write out error array extension
data quality initialization
correct for A to D conversion errors
subtract bias level computed from overscan img
Subtract bias image
combine observations to reject cosmic rays
process individual observations after cr-reject
apply shutter shading correction
Subtract dark image
flat field data
populate photometric header keywords
add individual repeat observations
process dithered images
L1
L1
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
/ CALIBRATION REFERENCE FILES
BPIXTAB
CCDTAB
ATODTAB
OSCNTAB
BIASFILE
CRREJTAB
SHADFILE
DARKFILE
PFLTFILE
DFLTFILE
LFLTFILE
PHOTTAB
IDCTAB
DITHTAB
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
bad pixel table
CCD calibration parameters
analog to digital correction file
CCD overscan table
bias image file name
cosmic ray rejection parameters
shutter shading correction file
dark image file name
pixel to pixel flat field file name
delta flat field file name
low order flat
Photometric throughput table
image distortion correction table
dither processing reference table
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
/ COSMIC RAY REJECTION ALGORITHM PARAMETERS
MEANEXP
SCALENSE
INITGUES
SKYSUB
SKYSUM
CRSIGMAS
CRRADIUS
CRTHRESH
BADINPDQ
REJ_RATE
CRMASK
=
=
=
=
=0
=
=
=
=
=0
=
reference exposure time for parameters
multiplicative scale factor applied to noise
initial guess method (MIN or MED)
sky value subtracted (MODE or NONE)
sky level from the sum of all constituent images
statistical rejection criteria
rejection propagation radius (pixels)
rejection propagation threshold
data quality flag bits to reject
rate at which pixels are affected by cosmic rays
flag CR-rejected pixels in input files (T/F)
/ PATTERN KEYWORDS
12
R4
R4
C03
C04
R4
C15
R4
R4
I2
R4
L1
PATTERN1
P1_SHAPE
P1_PURPS
P1_NPTS
P1_PSPAC
P1_LSPAC
P1_ANGLE
P1_FRAME
P1_ORINT
P1_CENTR
= NONE
=
=
=
=
=
=
=
=
=
primary pattern type
primary pattern shape
primary pattern purpose
number of points in primary pattern
point spacing for primary pattern (arc-sec)
line spacing for primary pattern (arc-sec)
angle between sides of parallelogram patt (deg)
coordinate frame of primary pattern
orientation of pattern to coordinate frame (deg)
center pattern relative to pointing (yes/no)
C18
C18
C10
I2
R4
R4
R4
C09
R4
C03
/ ENGINEERING PARAMETERS
CCDAMP
CCDGAIN
CCDOFSTA
CCDOFSTB
CCDOFSTC
CCDOFSTD
=
=
=
=
=
=
CCD amplifier read out configuration
commanded gain of CCD
commanded CCD bias offset for amplifier A
commanded CCD bias offset for amplifier B
commanded CCD bias offset for amplifier C
commanded CCD bias offset for amplifier D
C04
I2
I4
I4
I4
I4
/ CALIBRATED ENGINEERING PARAMETERS
ATODGNA
ATODGNB
ATODGNC
ATODGND
READNSEA
READNSEB
READNSEC
READNSED
=
=
=
=
=
=
=
=
calibrated gain for CCD amplifier A
calibrated gain for CCD amplifier B
calibrated gain for CCD amplifier C
calibrated gain for CCD amplifier D
calibrated read noise for amplifier A
calibrated read noise for amplifier B
calibrated read noise for amplifier C
calibrated read noise for amplifier D
R4
R4
R4
R4
R4
R4
R4
R4
/ TARGET ACQUISITION PARAMETERS
ACQTYPE
ACQNAME
=
=
type of acquisition
rootname of acquisition exposure
C15
C10
/ ASSOCIATION KEYWORDS
ASN_ID
ASN_TAB
ASN_MTYP
= NONE
= NONE
=
unique identifier assigned to association
name of the association table
Role of the Exposure in the Association
C10
C18
C12
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
= 1.0
= 32768.
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
scale factor for array value to physical value
physical value for an array value of zero
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
R8
R8
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
BSCALE
BZERO
13
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
/ READOUT DEFINITION PARAMETERS
CENTERA1
CENTERA2
SIZAXIS1
SIZAXIS2
BINAXIS1
BINAXIS2
=
=
=
=
=1
=1
subarray axis1 center pt in unbinned dect. pix
subarray axis2 center pt in unbinned dect. pix
subarray axis1 size in unbinned detector pixels
subarray axis2 size in unbinned detector pixels
axis1 data bin size in unbinned detector pixels
axis2 data bin size in unbinned detector pixels
I4
I4
I4
I4
I2
I2
/ PHOTOMETRY KEYWORDS
PHOTMODE
PHOTFLAM
PHOTZPT
PHOTPLAM
PHOTBW
=
=
=
=
=
observation configuration for photometric calib
inverse sensitivity, ergs/sec/cm2 per count
ST magnitude zero point
Pivot wavelength
RMS bandwidth of filter plus detector
C50
R8
R4
R4
R4
position number of this point in the pattern
I2
/ PATTERN KEYWORDS
PATTSTEP
=
/ REPEATED EXPOSURES INFO
NCOMBINE
=1
number of image sets combined during CR rejection
I2
/ DATA PACKET INFORMATION
FILLCNT
ERRCNT
PODPSFF
STDCFFF
STDCFFP
=0
=0
=F
=F
= x5569
number of segments containing fill
number of segments containing errors
podps fill present (T/F)
ST DDF fill present (T/F)
ST DDF fill pattern (hex)
I4
I4
L1
L1
C10
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
GOODMAX
GOODMEAN
SOFTERRS
MEANBLEV
MEANDARK
=
= 32767
=
=
=
=
=
=
number of good pixels
serious data quality flags
minimum value of good pixels
maximum value of good pixels
mean value of good pixels
number of soft error pixels (DQF=1)
mean value of bias level subtracted
mean value of dark counts subtracted
14
I4
I4
R4
R4
R4
R4
R4
R4
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
=
=
=
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
I4
I4
R4
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
GOODMAX
GOODMEAN
=
= 32767
=
=
=
number of good pixels
serious data quality flags
minimum value of good pixels
maximum value of good pixels
mean value of good pixels
I4
I4
R4
R4
R4
=
=
=2
=
=
=0
=1
=
=T
=
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
15
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
=
=
=
=
=
=
=
=
=
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
I2
C09
C09
R8
R8
C18
I4
I4
I4
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
END
16
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
19.4: HRC target acquisition header
SIMPLE
BITPIX
NAXIS
EXTEND
NEXTEND
GROUPS
DATE
FILENAME
FILETYPE
=T
=
=0
=T
=
=F
=
=
=
data conform to FITS standard
bits per data value
number of data axes
File may contain standard extensions
Number of standard extensions
image is in group format
date this file was written (yyyy-mm-dd)
name of file
type of data found in data file
L1
I2
I2
L1
I2
L1
C10
C18
C03
TELESCOP
INSTRUME
EQUINOX
= HST
=
= 2000.0
telescope used to acquire data
identifier for instrument used to acquire data
equinox of celestial coord. system
C03
C06
R4
/ DATA DESCRIPTION KEYWORDS
ROOTNAME
IMAGETYP
PRIMESI
=
=
=
rootname of the observation set
type of exposure identifier
instrument designated as prime
C09
C18
C06
proposer’s target name
right ascension of the target (deg) (J2000)
declination of the target (deg) (J2000)
C30
R8
R8
/ TARGET INFORMATION
TARGNAME
RA_TARG
DEC_TARG
=
=
=
/ PROPOSAL INFORMATION
PROPOSID
LINENUM
PR_INV_L
PR_INV_F
PR_INV_M
=
=
=
=
=
PEP proposal identifier
proposal logsheet line number
last name of principal investigator
first name of principal investigator
middle name / initial of principal investigator
I4
C15
C30
C20
C20
/ EXPOSURE INFORMATION
ORIENTAT
SUNANGLE
MOONANGL
SUN_ALT
FGSLOCK
DATE-OBS
TIME-OBS
EXPSTART
EXPEND
EXPTIME
EXPFLAG
=
=
=
=
= FINE
=
=
=
=
=
= NORMAL
position angle of image y axis (deg. e of n)
angle between sun and V1 axis
angle between moon and V1 axis
altitude of the sun above Earth’s limb
commanded FGS lock
(FINE,COARSE,GYROS,UNKNOWN)
R4
R4
R4
R4
C07
UT date of start of observation (yyyy-mm-dd)
UT time of start of observation (hh:mm:ss)
exposure start time (Modified Julian Date)
exposure end time (Modified Julian Date)
exposure duration (seconds)--calculated
Exposure interruption indicator
C10
C08
R8
R8
R4
C13
/ TARGET OFFSETS (POSTARGS)
POSTARG1
POSTARG2
=
=
POSTARG in axis 1 direction
POSTARG in axis 2 direction
R4
R4
/ DIAGNOSTIC KEYWORDS
OVERFLOW
CAL_VER
=
=
Number of science data overflows
CALACS code version
/ SCIENCE INSTRUMENT CONFIGURATION
17
I2
C24
CFSTATUS
OBSTYPE
OBSMODE
SCLAMP
NRPTEXP
SUBARRAY
DETECTOR
FILTER1
FILTER2
LRFWAVE
APERTURE
PROPAPER
CRSPLIT
=
=
=
=
=
=
=
=
=
=
=
=
=
configuration status (avail.,restr.,support.)
observation type - imaging or spectroscopic
operating mode
lamp status, NONE or name of lamp which is on
number of repeat exposures in set: default 1
data from a subarray (T) or full frame (F)
detector in use: WFC, HRC or SBC
element selected from filter wheel 1
element selected from filter wheel 2
proposed linear ramp filter wavelength
aperture name
proposed aperture name
number of cosmic ray split exposures
C11
C14
C08
C09
I2
L1
C03
C18
C18
R4
C16
C16
I2
/ CALIBRATION SWITCHES: PERFORM, OMIT, COMPLETE
STATFLAG
WRTERR
DQICORR
ATODCORR
BLEVCORR
BIASCORR
CRCORR
EXPSCORR
SHADCORR
DARKCORR
FLATCORR
PHOTCORR
RPTCORR
DITHCORR
=
=T
=
=
=
=
=
=
=
=
=
=
=
= OMIT
Calculate statistics?
Write out error array extension?
data quality initialization
correct for A to D conversion errors
subtract bias level computed from overscan img
Subtract bias image
combine observations to reject cosmic rays
process individual observations after cr-reject
apply shutter shading correction
Subtract dark image
flat field data
populate photometric header keywords
add individual repeat observations
process dithered images
L1
L1
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
C08
/ CALIBRATION REFERENCE FILES
BPIXTAB
CCDTAB
ATODTAB
OSCNTAB
BIASFILE
CRREJTAB
SHADFILE
DARKFILE
PFLTFILE
DFLTFILE
LFLTFILE
PHOTTAB
IDCTAB
DITHTAB
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
bad pixel table
CCD calibration parameters
analog to digital correction file
CCD overscan table
bias image file name
cosmic ray rejection parameters
shutter shading correction file
dark image file name
pixel to pixel flat field file name
delta flat field file name
low order flat
Photometric throughput table
image distortion correction table
dither processing reference table
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
C18
/ COSMIC RAY REJECTION ALGORITHM PARAMETERS
MEANEXP
SCALENSE
INITGUES
SKYSUB
SKYSUM
CRSIGMAS
CRRADIUS
CRTHRESH
BADINPDQ
REJ_RATE
CRMASK
=
=
=
=
=0
=
=
=
=
=0
=
reference exposure time for parameters
multiplicative scale factor applied to noise
initial guess method (MIN or MED)
sky value subtracted (MODE or NONE)
sky level from the sum of all constituent images
statistical rejection criteria
rejection propagation radius (pixels)
rejection propagation threshold
data quality flag bits to reject
rate at which pixels are affected by cosmic rays
flag CR-rejected pixels in input files (T/F)
/ ENGINEERING PARAMETERS
18
R4
R4
C03
C04
R4
C15
R4
R4
I2
R4
L1
CCDAMP
CCDGAIN
CCDOFSTA
CCDOFSTB
CCDOFSTC
CCDOFSTD
=
=
=
=
=
=
CCD amplifier read out configuration
commanded gain of CCD
commanded CCD bias offset for amplifier A
commanded CCD bias offset for amplifier B
commanded CCD bias offset for amplifier C
commanded CCD bias offset for amplifier D
C04
I2
I4
I4
I4
I4
/ CALIBRATED ENGINEERING PARAMETERS
ATODGNA
ATODGNB
ATODGNC
ATODGND
READNSEA
READNSEB
READNSEC
READNSED
=
=
=
=
=
=
=
=
calibrated gain for CCD amplifier A
calibrated gain for CCD amplifier B
calibrated gain for CCD amplifier C
calibrated gain for CCD amplifier D
calibrated read noise for amplifier A
calibrated read noise for amplifier B
calibrated read noise for amplifier C
calibrated read noise for amplifier D
R4
R4
R4
R4
R4
R4
R4
R4
/ TARGET ACQUISITION PARAMETERS
ACQTYPE
CENTMETH
CRELIM
CCDBIASS
BIASLEV
CHECKBOX
TARGAREA
=
=
=
=
=
=
=
type of acquisition
target acquisition centering method
Perform cosmic ray rejection in acquisition
CCD bias subtracted from Targ Acq Image?
CCD bias level used to process acquisition exp.
Size of checkbox for finding algorithms
Area of target (detector pixels)
C15
C16
L1
L1
R4
I2
R4
/ ASSOCIATION KEYWORDS
ASN_ID
ASN_TAB
ASN_MTYP
= NONE
= NONE
=
unique identifier assigned to association
name of the association table
Role of the Exposure in the Association
C10
C18
C12
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
= 1.0
= 32768.
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
scale factor for array value to physical value
physical value for an array value of zero
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
R8
R8
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
BSCALE
BZERO
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
19
R8
R8
R8
R8
C08
C08
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
/ READOUT DEFINITION PARAMETERS
CENTERA1
CENTERA2
SIZAXIS1
SIZAXIS2
BINAXIS1
BINAXIS2
=
=
=
=
=1
=1
subarray axis1 center pt in unbinned dect. pix
subarray axis2 center pt in unbinned dect. pix
subarray axis1 size in unbinned detector pixels
subarray axis2 size in unbinned detector pixels
axis1 data bin size in unbinned detector pixels
axis2 data bin size in unbinned detector pixels
I4
I4
I4
I4
I2
I2
/ PHOTOMETRY KEYWORDS
PHOTMODE
PHOTFLAM
PHOTZPT
PHOTPLAM
PHOTBW
=
=
=
=
=
observation configuration for photometric calib
inverse sensitivity, ergs/sec/cm2/s per count/s
ST magnitude zero point
Pivot wavelength
RMS bandwidth of filter plus detector
C50
R8
R4
R4
R4
/ REPEATED EXPOSURES INFO
NCOMBINE
=1
number of image sets combined during CR rejection
I2
/ DATA PACKET INFORMATION
FILLCNT
ERRCNT
PODPSFF
STDCFFF
STDCFFP
=0
=0
=F
=F
= x5569
number of segments containing fill
number of segments containing errors
podps fill present (T/F)
ST DDF fill present (T/F)
ST DDF fill pattern (hex)
I4
I4
L1
L1
C10
/ TARGET ACQUISITION PARAMETERS
TARGA1
TARGA2
APERA1
APERA2
APERLKA1
APERLKA2
MAXCHCNT
BOPOFFA1
BOPOFFA2
=
=
=
=
=
=
=
=
=
fsw located subarray axis1 coord. of target
fsw located subarray axis2 coord. of target
fsw located subarray axis 1 coord. of aperture
fsw located subarray axis 2 coord. of aperture
axis 1 detector pixel of acq aperture center
axis 2 detector pixel of acq aperture center
counts in the brightest checkbox
axis 1 offset (arcs) object moved off aperture
axis 2 offset (arcs) object moved off aperture
R4
R4
R4
R4
R4
R4
R4
R8
R8
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
GOODMAX
GOODMEAN
SOFTERRS
MEANDARK
MEANBLEV
=
= 32767
=
=
=
=
=
=
number of good pixels
serious data quality flags
minimum value of good pixels
maximum value of good pixels
mean value of good pixels
number of soft error pixels (DQF=1)
average of the dark values subtracted
average of all bias levels subtracted
20
I4
I4
R4
R4
R4
I4
R4
R4
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
=
=
=
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
I4
I4
R4
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
GOODMAX
GOODMEAN
=
= 32767
=
=
=
number of good pixels
serious data quality flags
minimum value of good pixels
maximum value of good pixels
mean value of good pixels
I4
I4
R4
R4
R4
=
=
=2
=
=
=0
=1
=
=T
=
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
21
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
=
=
=
=
=
=
=
=
=
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
I2
C09
C09
R8
R8
C18
I4
I4
I4
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
END
22
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
19.5: SBC science header
SIMPLE
BITPIX
NAXIS
EXTEND
NEXTEND
GROUPS
DATE
FILENAME
FILETYPE
=T
=
=0
=T
=
=F
=
=
=
data conform to FITS standard
bits per data value
number of data axes
File may contain standard extensions
Number of standard extensions
image is in group format
date this file was written (yyyy-mm-dd)
name of file
type of data found in data file
L1
I2
I2
L1
I2
L1
C10
C18
C03
TELESCOP
INSTRUME
EQUINOX
= HST
=
= 2000.0
telescope used to acquire data
identifier for instrument used to acquire data
equinox of celestial coord. system
C03
C06
R4
/ DATA DESCRIPTION KEYWORDS
ROOTNAME
IMAGETYP
PRIMESI
=
=
=
rootname of the observation set
type of exposure identifier
instrument designated as prime
C09
C18
C06
proposer’s target name
right ascension of the target (deg) (J2000)
declination of the target (deg) (J2000)
C30
R8
R8
/ TARGET INFORMATION
TARGNAME
RA_TARG
DEC_TARG
=
=
=
/ PROPOSAL INFORMATION
PROPOSID
LINENUM
PR_INV_L
PR_INV_F
PR_INV_M
=
=
=
=
=
PEP proposal identifier
proposal logsheet line number
last name of principal investigator
first name of principal investigator
middle name / initial of principal investigator
I4
C15
C30
C20
C20
/ EXPOSURE INFORMATION
ORIENTAT
SUNANGLE
MOONANGL
SUN_ALT
FGSLOCK
DATE-OBS
TIME-OBS
EXPSTART
EXPEND
EXPTIME
EXPFLAG
=
=
=
=
= FINE
=
=
=
=
=
= NORMAL
position angle of image y axis (deg. e of n)
angle between sun and V1 axis
angle between moon and V1 axis
altitude of the sun above Earth’s limb
commanded FGS lock
(FINE,COARSE,GYROS,UNKNOWN)
R4
R4
R4
R4
C07
UT date of start of observation (yyyy-mm-dd)
UT time of start of observation (hh:mm:ss)
exposure start time (Modified Julian Date)
exposure end time (Modified Julian Date)
exposure duration (seconds)--calculated
Exposure interruption indicator
C10
C08
R8
R8
R4
C13
/ TARGET OFFSETS (POSTARGS)
POSTARG1
POSTARG2
=
=
POSTARG in axis 1 direction
POSTARG in axis 2 direction
R4
R4
/ DIAGNOSTIC KEYWORDS
OVERFLOW
CAL_VER
=
=
Number of science data overflows
CALACS code version
/ SCIENCE INSTRUMENT CONFIGURATION
23
I2
C24
CFSTATUS
OBSTYPE
OBSMODE
SCLAMP
NRPTEXP
SUBARRAY
DETECTOR
FILTER1
FILTER2
LRFWAVE
APERTURE
PROPAPER
REPELLER
=
=
=
=
=
=
=
=
=
=
=
=
=
configuration status (avail.,restr.,support.)
observation type - imaging or spectroscopic
operating mode
lamp status, NONE or name of lamp which is on
number of repeat exposures in set: default 1
data from a subarray (T) or full frame (F)
detector in use: WFC, HRC or SBC
element selected from filter wheel 1
element selected from filter wheel 2
proposed linear ramp filter wavelength
aperture name
proposed aperture name
repeller voltage
C11
C14
C08
C09
I2
L1
C03
C18
C18
R4
C16
C16
C03
axis 1 MAMA offset
axis 2 MAMA offset
I2
I2
/ MAMA OFFSETS
MOFFSET1
MOFFSET2
=
=
/ LOCAL RATE CHECK IMAGE
LRC_XSTS
LRC_FAIL
=
=
Local Rate check image exists (T/F)
Local Rate Check Failed (T/F)
L1
L1
/ CALIBRATION SWITCHES: PERFORM, OMIT, COMPLETE
STATFLAG
WRTERR
DQICORR
GLINCORR
LFLGCORR
DARKCORR
FLATCORR
PHOTCORR
RPTCORR
DITHCORR
=
=T
=
=
=
=
=
=
=
= OMIT
Calculate statistics?
write out error array extension
data quality initialization
correct for global detector non-linearities
flag pixels for local and global nonlinearities
Subtract dark image
flat field data
populate photometric header keywords
add individual repeat observations
process dithered images
L1
L1
C08
C08
C08
C08
C08
C08
C08
C08
/ CALIBRATION REFERENCE FILES
BPIXTAB
MLINTAB
DARKFILE
PFLTFILE
DFLTFILE
LFLTFILE
PHOTTAB
IDCTAB
DITHTAB
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
= N/A
bad pixel table
MAMA linearity correction table
dark image file name
pixel to pixel flat field file name
delta flat field file name
low order flat
Photometric throughput table
image distortion correction table
dither processing reference table
C18
C18
C18
C18
C18
C18
C18
C18
C18
primary pattern type
primary pattern shape
primary pattern purpose
number of points in primary pattern
point spacing for primary pattern (arc-sec)
line spacing for primary pattern (arc-sec)
angle between sides of parallelogram patt (deg)
coordinate frame of primary pattern
orientation of pattern to coordinate frame (deg)
center pattern relative to pointing (yes/no)
C18
C18
C10
I2
R4
R4
R4
C09
R4
C03
PATTERN KEYWORDS
PATTERN1
P1_SHAPE
P1_PURPS
P1_NPTS
P1_PSPAC
P1_LSPAC
P1_ANGLE
P1_FRAME
P1_ORINT
P1_CENTR
= NONE
=
=
=
=
=
=
=
=
=
/ ASSOCIATION KEYWORDS
24
ASN_ID
ASN_TAB
ASN_MTYP
= NONE
= NONE
=
unique identifier assigned to association
name of the association table
Role of the Exposure in the Association
C10
C18
C12
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
= 1.0
= 32768.
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
scale factor for array value to physical value
physical value for an array value of zero
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
R8
R8
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
BSCALE
BZERO
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8
/ READOUT DEFINITION PARAMETERS
CENTERA1
CENTERA2
SIZAXIS1
SIZAXIS2
BINAXIS1
BINAXIS2
=
=
=
=
=1
=1
subarray axis1 center pt in unbinned dect. pix
subarray axis2 center pt in unbinned dect. pix
subarray axis1 size in unbinned detector pixels
subarray axis2 size in unbinned detector pixels
axis1 data bin size in unbinned detector pixels
axis2 data bin size in unbinned detector pixels
I4
I4
I4
I4
I2
I2
/ PHOTOMETRY KEYWORDS
PHOTMODE
PHOTFLAM
PHOTZPT
PHOTPLAM
PHOTBW
=
=
=
=
=
observation configuration for photometric calib
inverse sensitivity, ergs/sec/cm2 per count
ST magnitude zero point
Pivot wavelength
RMS bandwidth of filter plus detector
/ PATTERN KEYWORDS
25
C50
R8
R4
R4
R4
PATTSTEP
=
position number of this point in the pattern
I2
/ DATA PACKET INFORMATION
FILLCNT
ERRCNT
PODPSFF
STDCFFF
STDCFFP
=0
=0
=F
=F
= x5569
number of segments containing fill
number of segments containing errors
podps fill present (T/F)
ST DDF fill present (T/F)
ST DDF fill pattern (hex)
I4
I4
L1
L1
C10
/ ENGINEERING PARAMETERS
GLOBRATE
GLOBLIM
=
= UNDETERMINED
global count rate
R4
was global linearity level exceeded?
C16
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
GOODMAX
GOODMEAN
SOFTERRS
MEANDARK
=
= 32767
=
=
=
=
=
number of good pixels
serious data quality flags
minimum value of good pixels
maximum value of good pixels
mean value of good pixels
number of soft error pixels (DQF=1)
average of the dark values subtracted
I4
I4
R4
R4
R4
I4
R4
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
=
=
=
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
I4
I4
R4
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
26
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=1
=1
=
=
=
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
R4
R4
R8
R8
R8
/ IMAGE STATISTICS AND DATA QUALITY FLAGS
NGOODPIX
SDQFLAGS
GOODMIN
GOODMAX
GOODMEAN
=
= 32767
=
=
=
number of good pixels
serious data quality flags
minimum value of good pixels
maximum value of good pixels
mean value of good pixels
I4
I4
R4
R4
R4
=
=
=2
=
=
=0
=1
=
=T
=
=
=
=
=
=
=
=
=
=
extension type
bits per data value
number of data axes
length of first data axis
length of second data axis
number of group parameters
number of groups
number of fields in each table row
inherit the primary header
extension name
extension version number
rootname of the observation set
9 character exposure identifier
the minimum value of the data
the maximum value of the data
brightness units
length of constant array axis 1
length of constant array axis 2
values of pixels in constant array
C08
I2
I2
I4
I4
I2
I2
I2
L1
C06
I2
C09
C09
R8
R8
C18
I4
I4
I4
END
XTENSION
BITPIX
NAXIS
NAXIS1
NAXIS2
PCOUNT
GCOUNT
TFIELDS
INHERIT
EXTNAME
EXTVER
ROOTNAME
EXPNAME
DATAMIN
DATAMAX
BUNIT
NPIX1
NPIX2
PIXVALUE
/ World Coordinate System and Related Parameters
CRPIX1
CRPIX2
CRVAL1
CRVAL2
CTYPE1
CTYPE2
CD1_1
CD1_2
CD2_1
CD2_2
LTV1
LTV2
LTM1_1
LTM2_2
RA_APER
DEC_APER
PA_APER
=
=
= −32767.
= −32767.
= RA---TAN
= DEC--TAN
= 1.0
= 0.0
= 0.0
= 1.0
=0
=0
=1
=1
=
=
=
x-coordinate of reference pixel
y-coordinate of reference pixel
first axis value at reference pixel
second axis value at reference pixel
the coordinate type for the first axis
the coordinate type for the second axis
partial of first axis coordinate w.r.t. x
partial of first axis coordinate w.r.t. y
partial of second axis coordinate w.r.t. x
partial of second axis coordinate w.r.t. y
offset in X to subsection start
offset in Y to subsection start
reciprocal of sampling rate in X
reciprocal of sampling rate in Y
RA of reference aperture center
Declination of reference aperture center
Position Angle of reference aperture center
END
27
R8
R8
R8
R8
C08
C08
R8
R8
R8
R8
R4
R4
R4
R4
R8
R8
R8