[fitswcs] WCS documents

[Steve Allen]

On Tue 2001-09-18T11:09:03 -0400, Bob Hanisch hath writ:
> Sure.  A colleague was trying to compare VLA and HST (WFPC) data.  The VLA
> data had been processed with AIPS, HST data with IRAF and IDL.  The HST data
> had been rotated and resampled by another colleague, in IDL I think, and it
> was not clear if the WCS had been updated properly.  In addition, the VLA
> data uses the CDELT/CROTA WCS convention, and HST data uses the CD matrix.

And the upshot is that almost all of these FITS files are going to
need to be updated by specialized conversion software in order to
conform to whatever becomes the final WCS standard.

We could try to decide the issue based on not breaking compatibility
with existing software that uses interim and/or local standards, but
if we do that we risk the nasty situation of trying to resolve why
your application is more important than my application, and his, and
hers, etc.  I prefer to choose the clearest means of expressing the
information for transport.  Then the individual application owners can
create suitable translation algorithms.

The original FITS papers supplied the example of degenerate axes.
Other than for the sake of compatibility with some existing
applications what are reasons not to follow that example?

--
Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064
sla at ucolick.org      Voice: +1 831 459 3046     http://www.ucolick.org/~sla
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