PRIMARY Header¶
The PRIMARY header only needs to contain information on what detector this file corrects, along with any available information on how this file was generated. The ACS/WFC D2IMFILE PRIMARY header only includes:
SIMPLE = T / Fits standard
BITPIX = 16 / Bits per pixel
NAXIS = 0 / Number of axes
EXTEND = T / File may contain extensions
ORIGIN = 'NOAO-IRAF FITS Image Kernel July 2003' / FITS file originator
DATE = '2010-02-01T20:19:11' / Date FITS file was generated
IRAF-TLM= '2011-09-02T13:04:07' / Time of last modification
NEXTEND = 1 / number of extensions in file
FILENAME= 'v971826mj_d2i.fits' / name of file
FILETYPE= 'WFC D2I FILE' / type of data found in data file
OBSTYPE = 'IMAGING ' / type of observation
TELESCOP= 'HST' / telescope used to acquire data
INSTRUME= 'ACS ' / identifier for instrument used to acquire data
DETECTOR= 'WFC '
USEAFTER= 'Mar 01 2002 00:00:00'
COMMENT = 'D2I calibration file created by Warren Hack 29 APR 2010'
DESCRIP = 'Column-width correction file for WFC images------------------------'
PEDIGREE= 'INFLIGHT 11/11/2002 11/11/2002'
HISTORY
HISTORY Fixed column (or row) width correction file. This is applied
HISTORY as a correction to the input pixel position and the output of
HISTORY this correction is to be used as input to the polynomial and
HISTORY non-polynomial distortion corrections.
HISTORY
HISTORY For ACS WFC data, the correction is stored as an image extension
HISTORY (D2IMARR) with one row. Each element in the row specifies the
HISTORY correction in pixels for every pixel in the column (or row) in
HISTORY the science extension; for ACS WFC, the correction is in the X
HISTORY direction.
HISTORY
HISTORY For a more in-depth explanation of this file, please see the
HISTORY draft writeup at:
HISTORY http://stsdas.stsci.edu/stsci_python_epydoc/stwcs/fits_conventions.html
HISTORY wfc_ref68col_d2i.fits renamed to v961506lj_d2i.fits on Sep 6 2011
HISTORY v961506lj_d2i.fits renamed to v971826mj_d2i.fits on Sep 7 2011
In this case, most of the keywords not required by FITS describe how this file was computed while also describing how it should be applied.