[fitswcs] WCS -TAB complexities

[Mark Calabretta]

On Fri 2005/03/18 16:54:58 CDT, William Pence wrote
in a message to: fitswcs at nrao.edu

>There now exists a very simple way for application program developers to 
>calculate the coordinates within any FITS image, as long as the FITS image 
>uses any of the WCS coordinate conventions defined in Papers II and III 
>*except* the -TAB convention.  The application program only has to make 3 
>subroutine calls:

For the primary image header that is; things are also complicated for
image arrays in binary tables since the WCS information (of whatever
type) may be spread between the bintable header and the table itself.
Thus a wcsprm struct might only be partially constructed from the
bintable header, and need to be completed for each row of the table.
This would also require some handshaking between WCSLIB and CFITSIO
mediated by the user.

The most complicated situation is that for bintable image arrays with a
-TAB WCS; the WCS info is potentially spread across the bintable header
and table, with an additional -TAB bintable for each row of the table.

Mark Calabretta