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Procedure to add HISTORY (or COMMENT) line(s) to a FITS header


      The advantage of using SXADDHIST instead of SXADDPAR is that with
      SXADDHIST many HISTORY or COMMENT records can be added in a single call.

Calling Sequence

sxaddhist, history, header, [ /PDU, /COMMENT ]


history - string or string array containing history or comment line(s)
to add to the FITS header


header - FITS header (string array). Upon output, it will contain the
              specified HISTORY records added to the end

Optional Keyword Inputs

      /BLANK - If specified then blank (' ') keywords will be written
              rather than 'HISTORY ' keywords.
      /COMMENT - If specified, then 'COMMENT ' keyword will be written rather
              than 'HISTORY ' keywords.
              Note that according to the FITS definition, any number of
              'COMMENT' and 'HISTORY' or blank keywords may appear in a header,
              whereas all other keywords may appear only once.
LOCATION=key - If present, the history will be added before this
keyword. Otherwise put it at the end.
/PDU - if specified, the history will be added to the primary
data unit header, (before the line beginning BEGIN EXTENSION...)
Otherwise, it will be added to the end of the header.
              This has meaning only for extension headers using the STScI
              inheritance convention.


header - updated FITS header


sxaddhist, 'I DID THIS', header ;Add one history record
hist = strarr(3)
hist[0] = 'history line number 1'
hist[1[ = 'the next history line'
hist[2] = 'the last history line'
sxaddhist, hist, header ;Add three history records

Side Effects

      Header array is truncated to the final END statement
LOCATION overrides PDU.


D. Lindler Feb. 87
April 90 Converted to new idl D. Lindler
Put only a single space after HISTORY W. Landsman November 1992
Aug. 95 Added PDU keyword parameters
Converted to IDL V5.0 W. Landsman September 1997
LOCATION added. M. Greason, 28 September 2004.

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