[iaufwg] CRPIXj clarification

[William Pence]

Mark Calabretta wrote:
> On Mon 2008/06/23 14:13:17 -0400, William Pence wrote
> in a message to: IAU-FWG <iaufwg at nrao.edu>
> 
> Dear Bill,
> 
>> Before proceeding with the final IAUFWG vote on this matter, I should 
>> first call for any final discussion on this matter.  If you have any 
> 
> Can you remind me again of the reasons for removing the text "(e.g. as
> is done for random groups data)".

A couple people during the FITSBITS discussion had issues with this 
phrase, so it is much simpler to just delete it rather than spend time 
arguing over the wording of something that is not directly related to 
our primary purpose here, of clarifying that CRPIXj of the first image 
pixel has a value of 1, not 0.

As Eric Greisen pointed out, the WCS keywords are routinely used to 
define the coordinates within a single group array, so it is only the 
coordinate along the group axis itself that might not be regularly 
spaced and might be specified using the group parameter mechanism.  This 
is a subtle point that would likely not be grasped by most readers of 
this document.

regards,
Bill