WCS question

[Doug Mink]

Greg Hennessy wrote:
> 
> I am working on producing a set of images on CDROM that will have
> astrometry according to the Greisen and Calabretta A&A 1996 paper, but
> the four allowed values for RADECSYS are two for FK4, one FK5, and one
> geocentric apparent place. The images I will be working on are
> reduced against the ACT catalog. Are there any conventions to what
> RADECSYS should be for this? I would assume 'HIP' but would like some
> advice.

We talked about this at ADASS, and there was some agreement that the
RADECSYS for Tycho- and ACT- (and Hipparcos-) based images could be
HIPPARCOS (spelled out).  Pat Wallace has subroutines which convert
between the Hipparcos system and J2000, and I will be adding them
to my WCSTools package as soon as I get them from him.

-Doug Mink
 WCSTools developer ( http://tdc-www.harvard.edu/software/wcstools/ )