[AstroPy] Re: HIERARCH

Stephen Walton stephen.walton at csun.edu
Sun Apr 3 22:47:31 CDT 2005

FWIW, CFITSIO's handling of HIERARCH is documented at


As I read it, a new header keyword is checked for adherence to the FITS
standard (8 characters or less, alphanumerics plus underscore only).  If
it does not comply, then HIERARCH is prepended to the keyword and it is
written accordingly.  The only time an exception is raised is if the
keyword/value pair doesn't fit in 80 characters.


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