[wfc] WCS: call for votes! (July 10, 5pm)

[Peter Teuben]

Dear WFC members:

After more than ten years of debate and discussion, the first two of
several papers concerning World Coordinate Systems in FITS are now
ready for review.  These have been available for general review and
discussion (e.g. in [sci.astro.fits] and the [fitswcs] mailing list)
since last fall, and I hope that by now you are familiar with
them.

These papers, numbers I and II in a series of four, describe the
general formalism for WCS and the specific implementation for
celestial coordinates.  Paper III is concerned with spectral
coordinates, and will be brought forward for consideration after a bit
more public review.  Paper IV deals with distortions to ideal WCS and
is still being developed.  There should also be a Paper V, dealing
with temporal coordinates, once we can enlist someone to work on it!

Papers I and II have been in the works for over a decade.  This is not
because people have been lazy or derelict in their responsibilities.
Rather, doing WCS right is hard, and is the biggest challenge we have
ever addressed in FITS.  Eric Greisen and Mark Calabretta have
dedicated a major portion of their careers to getting it right, and we
owe them a tremendous debt for their diligence.  They have also been
open-minded on several pragmatic issues, so that, for example, the
proposed standard supports both a PC matrix (which separates scale and
rotation) and a CD matrix (which combines the two).  There are
rational and practical arguments for both notation systems.  It seems
counterproductive at this point to force a selection of one formalism
over the other.

I would like to hear your view on these papers within the next two
weeks.  That is perhaps a short time for such a major FITS initiative,
but these papers have been available for public review and discussion
for the past three years at least.  These are the most discussed and
comprehensive papers we have ever dealt with in FITS.  I believe that
we should endorse these papers, and then move on as soon as possible
to the spectral and distortion papers.

As you will see from the format (being in the A&A publication style),
these papers are going to be submitted to A&A (soon I hear).

Please respond to this message, no later than Wednesday July 10, with
your position concerning Papers I and II of the proposed FITS WCS
standard.

___ I approve of Papers I and II as establishing the WCS framework and
    the representation of WCS in sky coordinates.

___ I do not approve of Papers I and II.

Papers I and II (versioned at June 25, 2002) are now available for
review at Eric's website:

        http://www.aoc.nrao.edu/~egreisen

or use these direct links (with or without .gz at the end) using wget
or some URL grabber:

        http://www.aoc.nrao.edu/~egreisen/wcs_062502.ps     (paper I)
        http://www.aoc.nrao.edu/~egreisen/ccsf_062502.ps    (paper II)



Peter Teuben,
Chairman  WGAS Fits Committee