[fitsbits] WCS announcements

[Mark Calabretta]

Greetings,

This email contains three separate announcements.

1) WCS Papers I & II
--------------------
The first two world coordinate system papers were submitted to A&A on
2002/07/24 and accepted for publication with minor changes on 2002/09/09.
They should be on your library shelves now, or will appear shortly:

   Paper I,  "Representations of world coordinates in FITS"
   Greisen, E.W., & Calabretta, M.R. 2002, A&A, 395, 1061-1075

and

   Paper II, "Representations of celestial coordinates in FITS"
   Calabretta, M.R., & Greisen, E.W. 2002, A&A, 395, 1077-1122

Reprints of each of these are available from either

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

or

   http://www.atnf.csiro.au/~mcalabre/

We are pleased to advise that the three regional FITS committees and
IAU FWG have voted without dissent to accept these papers as FITS
standards.


2) WCS Paper III
----------------
In the meantime we have revised the spectral paper extensively, and are
now calling for comments with a view towards submitting the paper to A&A
in the new year:

   Paper III, "Representations of spectral coordinates in FITS"
   Greisen, E.W., Valdes, F.G., Calabretta, M.R., & Allen, S.L.
   A&A, (in preparation)

The latest draft, dated 2002/12/06, is available from either of the
above web sites.  As previously, the new draft of Paper III is colour-
coded to highlight changes made since the last publically announced
release on 2002/04/24.

Comments may be directed to the fitswcs mailing list - fitswcs at nrao.edu.
See http://listmgr.cv.nrao.edu/mailman/listinfo/fitswcs for more
information.


3) WCSLIB 3.0
-------------
With the publication of Papers I & II, and the advanced state of
Paper III, WCSLIB 3.0 is also nearing completion.  However, since it
differs significantly from the previous version I (MRC) have decided to
make the header files available for public comment before releasing it.
The main differences are:

   1) Fully vectorized interfaces (C preprocessor macros are available
      to implement the scalar interfaces of the proj.c, sph.c, and lin.c
      routines from WCSLIB 2.x).

   2) Implementation of Paper II, Sect. 2.5: User-specified (phi0, theta0).

   3) Implementation of Paper III (excluding "-TAB").

   4) Memory management is now implemented in the wcs.c routines.

   5) New extensible design should accomodate Paper IV (and any other)
      without further change to the function interfaces.

   6) FORTRAN library will be implemented as wrappers on the C library.

Regarding (4), as before, the wcsprm struct consists of a number of data
members that must be supplied and others that are computed from them.
In practice, it is expected that a FITS header parser would scan the FITS
header until it encountered the NAXIS (or WCSAXES) card which must occur
near the start of the header before any of the WCS keywords.  It would
then use wcsini() to allocate memory for arrays in the wcsprm struct and
set default values.  Then as it read and identified each WCS header card
it would load the value into the relevant wcsprm array element.  Finally
it would invoke wcsset(), either directly or indirectly, to initialize
the derived members of the wcsprm struct.  Thus, the FITS header parser's
job is now reduced to that of identifying and collecting WCS cards
(keeping track of alternate representations where necessary), and loading
them into a wcsprm struct which may then be passed on to other coordinate
routines for calls on WCSLIB.

The WCSLIB 3.0 header files and test programs are available from
http://www.atnf.csiro.au/~mcalabre/WCS.  Please send comments directly
to mcalabre at atnf.csiro.au.


Mark Calabretta, ATNF
Eric Greisen, NRAO