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    Provide information about the contents of a FITS file


    Information includes number of header records and size of data array.
    Applies to primary header and all extensions. Information can be
    printed at the terminal and/or stored in a common block
    This routine is mostly obsolete, and better results can be usually be
    performed with FITS_HELP (for display) or FITS_OPEN (to read FITS
    information into a structure)

Calling Sequence

    FITS_INFO, Filename, [ /SILENT , TEXTOUT = , N_ext =, EXTNAME= ]


    Filename - Scalar string giving the name of the FITS file(s)
              Can include wildcards such as '*.fits', or regular expressions
              allowed by the FILE_SEARCH() function. One can also search
              gzip compressed FITS files, but their extension must
              end in .gz or .ftz.

Optional Input Keywords

    /SILENT - If set, then the display of the file description on the
                terminal will be suppressed
      TEXTOUT - specifies output device.
              textout=1 TERMINAL using /more option
              textout=2 TERMINAL without /more option
              textout=3 <program>.prt
              textout=4 laser.tmp
              textout=5 user must open file, see TEXTOPEN
              textout=7 append to existing <program.prt> file
              textout = filename (default extension of .prt)
              If TEXTOUT is not supplied, then !TEXTOUT is used

Optional Output Keywords

      N_ext - Returns an integer scalar giving the number of extensions in
              the FITS file
      extname - returns a list containing the EXTNAME keywords for each

Common Blocks

      DESCRIPTOR = File descriptor string of the form N_hdrrec Naxis IDL_type
              Naxis1 Naxis2 ... Naxisn [N_hdrrec table_type Naxis
              IDL_type Naxis1 ... Naxisn] (repeated for each extension)
              For example, the following descriptor
                    167 2 4 3839 4 55 BINTABLE 2 1 89 5
              indicates that the primary header containing 167 lines, and
              the primary (2D) floating point image (IDL type 4)
              is of size 3839 x 4. The first extension header contains
              55 lines, and the byte (IDL type 1) table array is of size
              89 x 5.
              The DESCRIPTOR is *only* computed if /SILENT is set.


      Display info about all FITS files of the form '*.fit' in the current
              IDL> fits_info, '*.fit'
      Any time a *.fit file is found which is *not* in FITS format, an error
      message is displayed at the terminal and the program continues

Procedures Used


System Variables

      The non-standard system variables !TEXTOUT and !TEXTUNIT will be
      created by FITS_INFO if they are not previously defined.
      See TEXTOPEN.PRO for more info

Modification History

      Written, K. Venkatakrishna, Hughes STX, May 1992
      Added N_ext keyword, and table_name info, G. Reichert
      Work on *very* large FITS files October 92
      More checks to recognize corrupted FITS files February, 1993
      Proper check for END keyword December 1994
      Correctly size variable length binary tables WBL December 1994
      EXTNAME keyword can be anywhere in extension header WBL January 1998
      Correctly skip past extensions with no data WBL April 1998
      Converted to IDL V5.0, W. Landsman, April 1998
      No need for !TEXTOUT if /SILENT D.Finkbeiner February 2002
      Define !TEXTOUT if needed. R. Sterner, 2002 Aug 27
      Work on gzip compressed files for V5.3 or later W. Landsman 2003 Jan
      Improve speed by only reading first 36 lines of header
      Count headers with more than 32767 lines W. Landsman Feb. 2003
      Assume since V5.3 (OPENR,/COMPRESS) W. Landsman Feb 2004
      EXTNAME keyword can be anywhere in extension header again
                        WBL/S. Bansal Dec 2004
      Read more than 200 extensions WBL March 2005
      Work for FITS files with SIMPLE=F WBL July 2005
      Assume since V5.4, fstat.compress available WBL April 2006
      Added EXTNAME as an IDL keyword to return values. M. Perrin Dec 2007
      make Ndata a long64 to deal with large files. E. Hivon Mar 2008
      For GDL compatibility, first check if file is compressed before using
          OPENR,/COMPRESS B. Roukema/WL Apr 2010

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