Chris Beaumont's IDL Library

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coordinate systems

result = nextast(header)

This function returns a structure of astrometry parameters parsed from a FITS header. It is meant to mimic the IDL Astronomy User's Library routine 'EXTAST', but is generalized to handing N-dimensional data files (e.g. spectral data cubes). Note, however, that EXTAST handles a wider variety of astrometry parameters and, I'm sure, is much more robust for 2D FITS files

Error checking is limited. This was developed and tested for fits files using cdelt or cdi_j keywords, with no distortion or other fancy features.

Return value

An anonymous structure with the following tags: .NAXIS- the number of axes in the file .SZ - An NAXIS element array containing NAXIS1...NAXIS[N] .CD - An NAXIS x NAXIS array holding the CD/cdelt keywords. CD[i,j]=CD[I]_J. If the header uses CDELT keywords instead, they are converted to matrix form (CDELT1 = CD1_1) .CRPIX - An NAXIS element array containing the CRPIX keywords .CRVAL - An NAXIS element array containing the CRVAl keywords .CTYPE - An NAXIS element array containing the CTYPE keywords


header in required

A string array containing a fits header (ie, the output from mrdfits)

File attributes

Modifcation date: Mon Mar 22 16:17:13 2010
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