DEFINE FITS

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DEFINE FITS

            [SIC\]DEFINE FITS Var File [HEADER] [ [index] [T] [B] ]  [/GLOBAL]

        Define variables associated to the keywords and data  of  a  FITS  file.
        The defined variables depend on the FITS file content. Both "basic" FITS
        files and FITS extension (XTENSION) are handled.

        The HEADER keyword indicates to read only the FITS  Headers  (which  in-
        cludes any Extension), not the main data array.

        An 'index' value may be added to read only the 'index'-th extension.

        With  'B'  code  (stands for Basic): define only the basic keywords, not
        proprietary keywords. In particular suppress HIERARCH keyword  structure
        present in ESO FITS headers.

        The  'T' code may be added to get all multidimensional arrays transposed
        (depending on how the FITS file was written, sometimes the dimensionali-
        ty  of  the  SIC variables created from the FITS structure is not handy.
        Using the transposition code can be a solution then).

        The 'index', 'T' and 'B' codes can appear in any order.

        For basic FITS data, the following variables are defined
           VAR%NDIM       Integer        Number of dimensions
           VAR%DIM        Integer[4]     Dimensions
           VAR%CONVERT    Double[3,4]    Conversion formulae for the 4 axes:
                                         Reference pixel, Value at reference
                                         pixel, Increment
           VAR%DATA       Real           FITS data array
        The variables are defined as part of a structure.  GreG  command  LIMITS
        /RGDATA A recognizes such a basic FITS structure in much the same way as
        GILDAS images.

        The DEFINE FITS command tries to define a SIC structure  which  contains
        all  FITS  keywords,  as  well as all binary and ASCII tables located in
        FITS extensions.

        Support for Random groups (although this is an obsolescent  FITS  struc-
        ture, it is still widely used) is also available.

        DEFINE  FITS only works to read FITS files, but not to create them.  See
        VECTOR\FITS to write FITS files (and also read them, but only  the  main
        array so far).