Hi Chris,

"...For some reason Charon believed the sun was up and that the
image was taken here (642)."

If that's what it says in Charon's settings menu, then that's the MPC
code the program will use. Unfortunately, it can't get the MPC code from
the FITS header. (Not in any reliable or standard way, that is. I'm sure
the MPC code is sometimes stored in FITS headers, but I'd be gobsmacked
if any two programs stored them in the same way. Setting it through Charon
is more reliable.)

I'm pleased to hear from some folks using the program. Although I've
done very little except maintenance on it for some years, I was tempted to
make a major change when John Greaves pointed out this paper to me:

http://arxiv.org/abs/0910.2233

The program described in the article loads up an image and
automatically figures out where that image is in the sky, given
a pretty rough estimate of the image scale. I'd considered some
similar tricks long ago, but didn't think it would run very
quickly. Seems it's actually quite fast, and I can see several
ways in which it could be both simplified and sped up. The result
would be that Charon could be much more reliable and the need for
user control would mostly go away: the program could run in an
almost totally automated fashion. But it would be a _big_ project;
I doubt I'll do it any time soon!

-- Bill