[fitswcs] Status of WCS negotiations

[William Pence]

Don Wells wrote:

> OK, readers of
> 'fitswcs', it is time to declare your requirements:
> 
>     Who among you need multiple WCS solutions?

The X-ray and gamma ray event tables, with X and Y coordinate columns
generally could use multiple WCS solutions, e.g., coordinates within the
detector, one or more sets of coordinates in the telescope focal plane, and
one or more sets of coordinates projected on the sky.  Some missions also
have an objective grating mode where each point on the image may have one or
more energies/wavelengths associated with it.

>     Do you need multiple entire sets of WCS keywords, including CDij?

In practice we have rarely needed a rotation term or the CDij matrix, but in
principle it would be good to be able to support multiple sets of all the
keywords.

____________________________________________________________________
Dr. William Pence                          pence at tetra.gsfc.nasa.gov
NASA/GSFC Code 662         HEASARC         +1-301-286-4599 (voice)     
Greenbelt MD 20771                         +1-301-286-1684 (fax)