[fitsbits] Maximum number of extensions

[William Pence]

Richard West wrote:
> 
> Perhaps a daft question, but not one I've found an answer too in any of the
> FITS documentation I've looked in. Is there a formal limit to the number of
> extensions (HDUs) in a FITS file?
> 
> CFITSIO seems to be quite happy creating and manipulating files with large
> numbers of extensions (ie. tens of thousands), though FTOOLs doesn't like
> any file with more than 1000.
> 
> So I'm wondering if this is an artificial limit imposed by FTOOLs, or
> CFITSIO being (over-)flexible.

There is nothing in the FITS Standard definition document that limits the
number of extensions in a FITS file.  CFITSIO used to only support up to
1000 HDUs in a FITS file, which is why some of the ftools tasks have this
limit.  In July 2002 CFITSIO was modified to support an unlimited number of
HDUs in a FITS file.

Bill Pence
-- 
____________________________________________________________________
Dr. William Pence                          William.D.Pence @ nasa.gov
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