more on FITS and VO

[Patrick P Murphy]

On Thu, 27 Nov 2003 12:29:38 +0000 (GMT), Guy Rixon <gtr at ast.cam.ac.uk>
   said: 

> On Wed, 26 Nov 2003, Robert Hanisch wrote:

>> I've been asked to poll the VO community concerning the proposed FITS MIME
>> type and a restriction that has been suggested:

(quoting from Bill Pence):

>>> Do you, or other members of the VO community, have any objections to
>>> this change to the FITSMIME proposal?  The effect of this one word
>>> change (from 'must' to 'should') would be to allow null images (with
>>> one or more NAXISn keywords = 0) to be given the mime type

Note: NAXIS**n**, i.e. NAXIS1 or NAXIS2 etc.  

>>> "image/fits".  Without this change in wording this would not be
>>> allowed, and such null images would have to be given the mimetype
>>> "application/fits".  This appears to be the last question to be
>>> resolved before the FITS committees can vote on the proposal (very
>>> soon I hope).

> This change sounds unhelpful.  Something with NAXIS=0 isn't an image; 

While it's a semantic point, what the proposal said did not refer to the
NAXIS (number of axes) keyword, but to the value of one or more of the
NAXIS1, NAXIS2, etc. keywords being zero.  This feature is most often
used by the non-optical Astronomy community (Radio, X-ray, etc).

> you can't display it in an image viewer.  Surely the point of
> image/fits is to separate those datasets that can be passed to a
> generic image-viewer from those where the receiving programme needs to
> know the semantics of the data?

Point taken, but what should we then do about our UV-DATA and other
files that qualify as valid FITS files but have NAXIS1=0; are they to be
excluded from using the image/fits MIME type?

				- Pat
-- 
 Patrick P. Murphy, Ph.D.           Division Head, CV Computing, NRAO
 Home: http://goof.com/~pmurphy/    Work: http://www.nrao.edu/~pmurphy/
 "Laws of nature are...just parochial by-laws in our cosmic patch"
                                                    - Martin Rees