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HROTATE

HROTATE

Name


    HROTATE

Purpose


    Apply the IDL ROTATE function and update astrometry in a FITS header

Explanation


    Apply the intrinsic IDL ROTATE function to an image and update
    astrometry in the associated FITS header.

Calling Sequence


    HROTATE, oldim, oldhd, newim, newhd, direction
              or
    HROTATE, oldim, oldhd, direction
                     

Inputs


    OLDIM - the original image array
    OLDHD - the original FITS image header, string array
    DIRECTION - Scalar integer (0-7) specifying rotation direction,
              exactly as specified by the IDL ROTATE function.
        Direction Transpose? Rot. CCW X1 Y1
      ----------------------------------------
      0 No None X0 Y0 (no change)
      1 No 90 -Y0 X0
      2 No 180 -X0 -Y0
      3 No 270 Y0 -X0
      4 Yes None Y0 X0
      5 Yes 90 -X0 Y0
      6 Yes 180 -Y0 -X0
      7 Yes 270 X0 -Y0

Optional Outputs


    NEWIM - the rotated image, with the same dimensions as Oldim
    NEWHD - header for newim containing updated astrometry info
              If output parameters are not supplied, the program
              will modify the input parameters OLDIM and OLDHD
              to contain the rotated image and updated header.

Optional Keyword Output


    ERRMSG - If this keyword is supplied, then any error mesasges will be
              returned to the user in this parameter rather than depending on
              on the MESSAGE routine in IDL. If no errors are encountered
              then a null string is returned.

Example


    Rotate an image exactly 90 degrees counterclockwise and update the
    FITS image array and header.
      IDL> HROT, im, h, im_new, h_new, 1

Procedure


      The image array is rotated using the ROTATE function.
      The CD (or CROTA) and CRPIX parameters, if present in the FITS header,
      are updated for the new rotation.
      History records are also added to the header

Restrictions


    Does not work Guide Star Survey (GSS) astrometry. Use GSSS_STDAST to
    first convert

Procedures Used


    CHECK_FITS(), SXADDPAR, EXTAST

Modification History


    Written, Mar 1997 W. Landsman, Hughes STX
    Work for non-square images W. Landsman June 1998 Raytheon STX
    Fix for different plate scales, and CROTA2 defined, November 1998
    Added ERRMSG, Use double precision formatting, W. Landsman April 2000
    Consistent conversion between CROTA and CD matrix W. Landsman Oct 2000
    Correct update when CROTA keyword present W. Landsman June 2003
    Update CDELT for AIPS-style astrometry headers M. Perrin/WL Jul 2003
    Convert GSS astrometry to WCS W. Landsman November 2004
    Work even if no astrometry present, just update NAXIS* WL June 2011



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