[fitswcs] Forwarded message: WCS activity

[Mark Calabretta]

------- Forwarded Message

Date: Thu 2001/06/07 12:05:53 -0400
From: Don Wells <dwells at cv.nrao.edu>
To:   Steve Allen <sla at ucolick.org>
CC:   Eric Greisen <egreisen at NRAO.EDU>,
      Mark Calabretta <Mark.Calabretta at atnf.CSIRO.AU>,
      Ernst Raimond <exr at nfra.nl>, Peter Teuben <teuben at astro.umd.edu>,
      Preben Grosbol <pgrosbol at eso.org>,
      Osamu Kanamitsu <kanamitu at fukuoka-edu.ac.jp>,
      Patrick Wallace <ptw at star.rl.ac.uk>,
      William Pence <pence at tetra.gsfc.nasa.gov>, "Doug Tody" <tody at noao.edu>,
      "Lindsey Davis" <davis at noao.edu>, "Frank Valdes" <valdes at noao.edu>,
      Don Wells <dwells at NRAO.EDU>
Subject: Re: WCS activity

Dear Steve, (plus Eric, Mark, Ernst, Peter, Preben, Osamu, Pat, Bill,
                  Doug, Lindsey and Frank)

Steve Allen writes:
 > Is there any FITS WCS activity?

Yes. 

It was obvious in 2000 that Section 5 of WCS-III is incomplete.  I
have long suspected that a proper solution to the 'spectral coordinate
variation with other coordinates' problem will require that additional
features or conventions be added to WCS-I.  I raised this question
many months ago when I presented the WCS-I/II/III documents to the
committees.  I urged the community to consider the question, and to
respond to it.  I hoped that I would receive assurances that no
changes to WCS-I are needed, so that I would be able to recommend that
WCS-I and WCS-II proceed to a vote. I have not received the necessary
assurances.  If WCS-I cannot proceed, neither can WCS-II.

Only one group of astronomical software people had anything to say to
me on the relationship of WCS-I to WCS-III.5; this was the IRAF group
at NOAO.  I began communicating with them privately regarding
WCS-III.5 and other WCS issues. I said nothing publicly because other
FITS people seemed unconcerned about the WCS-III.5 issue.  Also, it
was clear to me that we needed some new ideas, and that the creation
of those ideas would be most likely to occur in a private discussion
context.  This is why I have been publicly silent for many months.

In recent weeks Frank Valdes of the IRAF group has produced two draft
proposal documents, on which I have commented. These proposals appear
to me to be close to achieving a comprehensive general solution of the
problem posed in WCS-III.5.  Frank has informed me that he now has a
prototype implementation of these proposals as part of the IRAF MWCS
routines.  Doug, Lindsey and Frank need to complete their own internal
review of their proposals before distributing them; Doug expects that
this process will take two or three weeks more, until roughly the end
of June.  I expect that the IRAF group will submit their proposals to
Eric and Mark for review at that time.  These proposals from the IRAF
group will recommend that some new features and conventions be added
to both WCS-I and WCS-III.

Regards,
Don

PS: I am sending this message to a limited list of people rather than
    to the 'fitswcs' mailing list because I think that the limited
    list needs to know what has been happening, and because I expect
    that we will soon be able to announce availability of the actual
    proposal documents.  However, recipients of this message should
    feel free to forward copies of it as they see fit.  In particular,
    I suggest that Eric and Mark and the the FITS committee officers
    forward copies of this message to people who enquire about the
    status of the WCS proposals.

- -- 
  Donald C. Wells      Scientist - GBT Project        dwells at nrao.edu
                    http://www.cv.nrao.edu/~dwells
  National Radio Astronomy Observatory                +1-434-296-0277
  520 Edgemont Road,   Charlottesville, Virginia       22903-2475 USA

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