Hi folks,

Richard, I've not commented on the troubles with downloading
DSS images because I had no real idea as to what might cause the
trouble... but it occurs to me to ask: how about downloading A2.0
and/or GSC-2.2 data? That is, is the problem a "generic downloading
anything, doesn't matter what" sort of problem, or a "downloading
DSS images only" problem?

Lawrence, it's true that I've done next to nothing with Charon
for a while now, aside from occasional bug fixes. I am slightly
unhappy about that, but I've had a few too many projects going on
anyway; something has had to give, and Charon has been it.

Charon was (as far as I know) the first program to do "automated
astrometry", i.e., figuring out the match between star patterns
in an image and patterns in a star catalog. I originally wrote it
after some folks mentioned to me that they were spending more time
reducing their images and extracting astrometry than they were in
gathering the images. For folks doing a lot of astrometry, it's
been mostly supplanted by Bob Denny's excellent _PinPoint_ software.

A while back, I took a stab at turning Charon into a
user-supported open-source program, and gave a talk in which I
evangelized the idea that astrometry software should be provided
in that manner:

http://www.projectpluto.com/mpw_talk.htm

Since then, I've posted all of Charon's source code, and a
few people have used part or all of the code in their own
projects. But it hasn't quite taken off as I'd hoped it might.
Charon does have a lot of nifty stuff in it, and I'd hate to see
it all go to waste... but I gotta have priorities.

Should I return to Charon, though, a port to Windows would
not be much of a priority. The graphics are almost never a
problem; I've heard from _very_ few people who found that all the
high-res modes failed, and those who did usually found that the
'-;' switch got one or two such modes to work. I have some
interest in rigging it up to support several new astrometric
catalogues (Bordeaux, CMC-12, B1.0, and (when it comes out)
UCAC-2) and in adding a good algorithm for measuring trailed
images, as described at

http://www.projectpluto.com/trailed.htm

...but not much in the way of plans beyond that.

Regarding the duplicate 2001 HT50: this was originally known
as plain ol' "2001 HT50", and now known as "C/2001 HT50", and
Guide isn't bright enough to realize that it's the same comet
with two different names. Similar problems arose with some
recently-numbered comets such as P/Helin-Lawrence (152P),
P/Helin (151P), and P/Shoemaker 3 (155P).

You've got two choices here. You can download a replacement
'cometg.dat' file:

http://www.projectpluto.com/cometg.zip

in which the names have been changed to protect against
duplication. Or you can wait for the next update, which will
do the translation for you (just fixed it to do that).

Incidentally, after doing this, you have to persuade Guide
to re-read 'cometg.dat' and extract the currently bright comets.
Easiest way to do that is to set its time ahead/back by a couple
of years, then return to the present. It will then throw out
the "bad" comets and keep the "right" ones.

-- Bill