[AstroPy] Inverting SkyCoord spherical offset, transformations

[Warren Hack]

David,

Thank you!  That solution allowed me to apply the offsets I have to the 
test images and align them (better) to the astrometric catalog positions.

The real issue in my opinion would be the non-intuitive nature of the 
required solution, especially for someone not actively developing the 
astropy coordinates code.  I would suggest to the astropy developers 
that they therefore include this solution, or whatever may improve upon 
it (if possible), in the documentation. It would serve as a follow-up to 
the example already in the docs which served as the starting point for 
this question, and show how to 'round-trip' the information being computed.

For now, though, my problem has been solved.

Thanks again!
Warren