wcsinit.c

WCSTools subroutines to read WCS information from FITS headers:

Subroutines

wcsinit (hstring) sets a WCS structure from an image header

wcsninit (hstring,lh) sets a WCS structure from an image header

wcsninit (char *hstring, int lhstring)

Set up a WCS structure from a FITS image header lhstring bytes long.
Returns a pointer to struct WorldCoor

hstring: Character string containing FITS header information in the format keyword= value [/comment]
lhstring: Length of FITS header in bytes

wcsinit (char *hstring)

Set up a WCS structure from a FITS image header
Returns a pointer to struct WorldCoor

hstring: Character string containing FITS header information in the format keyword= value [/comment]; Assumed to be null-terminated

Use Digitized Sky Survey header information, FITS WCS keywords for 8 (AIPS) or 26 (proposed FITS) projections, or an approximate plane-tangent projection. The approximation uses the RA and DEC keywords as the coordinates of the central pixel of the image and SECPIX (or SECPIX1 and SECPIX2) keywords as the plate scale at the center in arcseconds per pixel.

Set the equinox and radecsys variables in the wcs data structure based on image header keyword values. If RADECSYS is not present, the coordinate system is set from EQUINOX (1950 implies FK4, 2000 implies FK5) or EPOCH, if EQUINOX is not present.

Last updated 15 September 1998 by Doug Mink dmink@cfa.harvard.edu

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