Name

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    ADD_DISTORT

Purpose

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    Add the distortion parameters in an astrometry structure to a FITS header.

Explanation

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    Called by PUTAST to add SIP (http://fits.gsfc.nasa.gov/registry/sip.html )
    in an astrometry structure to a FITS header
   
    Prior to April 2012, PUTAST did not add distortion parameters so one
    had to call ADD_DISTORT after PUTAST.
    IDL> putast,h ,astr0
    IDL> add_distort,h,astr0

Calling Sequence

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    add_distort, hdr, astr

Inputs

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    HDR - FITS header, string array. HDR will be updated to contain
            the supplied astrometry.
    ASTR - IDL structure containing values of the astrometry parameters
            CDELT, CRPIX, CRVAL, CTYPE, LONGPOLE, PV2, and DISTORT
            See EXTAST.PRO for more info about the structure definition

Procedures Used

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      SXADDPAR, TAG_EXIST()

Revision History

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      Written by W. Landsman May 2005
      Enforce i+j = n for ij coefficients of order n W. Landsman April 2012