Name

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  NEXTAST

Purpose

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  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

Category

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  coordinate systems

Calling Sequence

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  result=NEXTAST(header)

Inputs

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

Outputs

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  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

Restrictions

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  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.
 

Modification History

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  Written by: Chris Beaumont, July 27, 2008