Hi Owen,

True, UCAC-3 is quite far from perfect. There are some really
weird things in it. But I didn't really have much better to offer.

Guides 1.0 through 8.0 were based on the Hubble Guide Star Catalog
(part of what I had in mind when I chose the name). At the time,
GSC was an utterly amazing leap forward over anything else available.
It's almost obsolete now, but you'll notice that you can still get
decent star charts with it... which is what most people use it for.

UCAC-3 will provide about five times the star density. The magnitudes
aren't photometric, but neither are they the total junk provided by
GSC (and 2MASS magnitudes are provided as well). The proper motions
have minor issues for all stars and _major_ issues for some stars
(and to make it more annoying, you can't really tell in which class
a given star falls). However, GSC provided us with no proper motion
data at all.

I do regard UCAC-3 with some disappointment. It took a long, long
time to come out, which I took as a sign that it was Going to Be Done
Right. When I got the DVD, I quickly found all sorts of issues, some
of the "how the %$!* could you not have found this?" sort (I don't think
anyone did the equivalent of beta-testing the catalog).

But despite that, I still consider it a major advance over GSC and
am happy to have it as the basic star catalog for Guide 9.0.

-- Bill