[fitswcs] Detector distortion correction representations in FITS

[Peter Bunclark]

On Tue, 1 Feb 2000, Doug Mink wrote:

> Mark Calabretta wrote:
> 
> > However, my answer is basically unchanged for the reasons previously given.
> 
> I did something like this with the TAN + polynomial I implemented in WCSTools.
> If the polynomial keywords are present, I simply ignore the CD matrix, which
> is present for software which doesn't include my subroutines.  I build the

We're not getting close to saying, the CD matrix is too simplistic and
you should have a `CD' polynomial instead?  Which takes me back to an
earlier point, I'd rather use the geometric projection which most closely
matched the optical system (ARC for Schmidt, TAN for prime-focus are the 
two closest to my heart) and apply the lowest-possible-powered
correction to that to fit the real world.

Pete.
>