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44.3 Header Keywords

Table 44.3 lists the header keywords found in a WF/PC-1 .c0h image header that many observers are likely to find useful; the STSDAS tasks hedit or imhead can be used to view any or all of the header and group keywords. WF/PC-1 keywords include items such as observing mode, integration time, and filters used, calibration steps performed and reference files used, and the properties of the data itself (e.g., number of groups, coordinates, scale, flux units, image statistics, and more). In Table 44.3, the group keywords are GROUPS through PHOTBW; keywords INSTRUME through SEQNAME are the general keywords.


WF/PC-1 Header Keywords

Keyword

Description

Information about the groups

GROUPS

Multi-group image?

GCOUNT

Number of groups (number of detectors read out)

Coordinate-related keywords

CRVAL1

RA of reference pixel (deg)

CRVAL2

Declination of reference pixel (deg)

CRPIX1

X coordinate of reference pixel

CRPIX2

Y coordinate of reference pixel

CD1_1

Partial of RA with respect to x

CD1_2

Partial of RA with respect to y

CD2_1

Partial of declination with respect to x

CD2_2

Partial of declination with respect to y

Image Contents

ORIENTAT

Orientation of image (deg)

DETECTOR

CCD detector: WF 1-4, PC 5-8

Bias level information (columns 3-14 of the .x0h/.x0d file)

DEZERO

Bias level from EED extended register

BIASEVEN

Bias level based on average of odd columns in x0h/x0d file

BIASODD

Average bias level based on average of even columns

Pixel statistics

GOODMIN

Minimum value of "good" pixels (not flagged in DQF)

GOODMAX

Maximum value of "good" pixels

DATAMEAN

Mean value of "good" pixels

GPIXELS

Number of good pixels

Photometry keywords

PHOTMODE

Photometry mode

PHOTFLAM

Inverse sensitivity (units of erg/sec/cm2/Å for 1 DN/sec)

PHOTZPT

Zero point (currently -21.10, if DOPHOTOM = yes)

PHOTPLAM

Pivot wavelength (in angstroms)

PHOTBW

rms bandwidth of filter (in angstroms)

Image keywords

INSTRUME

Instrument used; always WFPC for either WF or PC

ROOTNAME

Rootname of the observation set

FILETYPE

SHP - standard header packet

EXT - extracted engineering file

EDQ - EED data quality file

SDQ - science data quality file

SCI - science data file

CAMERA

Camera in use: WF (wide-field), PC (planetary)

MODE

Mode: FULL (full resol.) or AREA (2x2 pixel summation)

SERIALS

Serial clocks: ON, OFF

Data type keywords

IMAGETYP

DARK/BIAS/INTFLAT/KSPOTS

/EXTERNAL/EARTH-CAL

CDBSFILE

GENERIC/BIAS/DARK/PREF/FLAT/MASK/ATOD/NO Is the image a reference file and if yes, type is specified

Reference file selection keywords

DATE

Date file written (dd/mm/yy)

FILTNAM1

First filter name

FILTNAM2

Second filter name; blank if none

FILTER1

First filter number (0-48) (Historical, but used in SOGS)

FILTER2

Second filter number (0-48)

PFILTER1

Preflash Filter 1 number (0-48); always 1=F122M

PFILTER2

Preflash Filter 2 number (0-48); always 47=F1083N (WF) 35=F1042M (PC)

SHUTTER

Shutter in place during preflash or INTFLAT (A, B, or Unknown)

Calibration switches

MASKCORR

Do mask correction: YES, NO, DONE

ATODCORR

Do A-to-D correction: YES, NO, DONE

BLEVCORR

Do bias level correction: YES, NO, DONE

BIASCORR

Do bias correction: YES, NO, DONE

PREFCORR

Do preflash correction: YES, NO, DONE

PURGCORR

Do purge correction-always NO

DARKCORR

Do dark correction: YES, NO, DONE

FLATCORR

Do flatfield correction: YES, NO, DONE

DOSATMAP

Output Saturated Pixel Map-always NO

DOPHOTOM

Fill photometry keywords: YES, NO, DONE

DOHISTOS

Make histograms: YES, NO, DONE

Calibration reference files used1

MASKFILE

Name of the input DQF of known bad pixels

ATODFILE

Name of the A-to-D conversion file

BLEVFILE

Engineering file with extended register data

BLEVDFIL

Engineering file data quality file (DQF) name

BIASFILE

Name of the bias frame reference file

BIASDFIL

Name of the bias frame reference DQF

PREFFILE

Name of the preflash reference file

PREFDFIL

Name of the preflash reference DQF

PURGFILE

Name of the purge reference file (dummy name)

PURGDFIL

Name of the purge reference DQF (dummy name)

DARKFILE

Name of the dark reference file

DARKDFIL

Name of the dark reference DQF

FLATFILE

Name of the flatfield reference file

FLATDFIL

Name of the flatfield reference DQF

PHOTTAB

Name of the photometry calibration table

SATURATE

Data value at which saturation occurs

(always 4095 for WF/PC-1, which includes the bias)

Ephemeris data

PA_V3

Position angle of V3 axis of HST

RA_SUN

Right ascension of the sun (deg)

DEC_SUN

Declination of the sun (deg)

EQNX_SUN

Equinox of the sun

Exposure Information

WEXPODUR

Commanded duration of exposure (seconds). For exposures less than 1/2 sec, WEXPODUR is set to 0.

PREFTIME

Predicted preflash time (sec); 30 for WFC and 8 for PC

DARKTIME

Estimate of darktime (in sec)

FGSLOCK

Commanded FGS lock (FINE, COARSE, GYROS, UNKNOWN)

Timing information

DATE-OBS

UT date of start of observation (dd/mm/yy)

TIME-OBS

UT time of start of observation (hh:mm:ss)

EXPSTART

Exposure start time (Modified Julian Date)

EXPEND

Exposure end time (Modified Julian Date)

EXPTIME

Exposure duration (seconds)

EXPFLAG

How exposure time was calculated. (NORMAL, INTERRUPTED, INCOMPLETE, EXTENDED, UNCERTAIN, INDETERMINATE, or P REDICTED)

Proposal information

TARGNAME

Proposer's target name

RA_TARG

Right ascension of the target (deg) (J2000)

DEC_TARG

Declination of the target (deg) (J2000)

1 Calibration reference file keywords are populated even when not used.



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Copyright © 1997, Association of Universities for Research in Astronomy. All rights reserved. Last updated: 01/14/98 16:04:09