Hi Lawrence,

They're shipping. More info on this on the Minor Planet Mailing List :

http://groups.yahoo.com/group/MPML/

Basically, DVDs started shipping recently to everyone who was on the UCAC3
list. A few people have received their copies (I've not received mine yet;
fortunately, I had a "pre-release" copy, complete except for some APASS
photometry, that I was able to use for testing/writing code.)

The new data looks to be a decent improvement on UCAC3. UCAC3 had some
rather unfortunate aspects to it. A lot of stars had suspiciously high
proper motions. There were "duplicate" stars for about one million objects
(fortunately, these were very easy to detect and are suppressed in Guide).
Due to a processing error, about a million stars that really _should_ have
appeared were omitted from UCAC3.

UCAC4 fixes these problems, and adds in APASS photometry. A somewhat
outdated description of APASS is available at :

http://www.aavso.org/apass

The data used with UCAC4 is from Data Release 6. Magnitudes are provided
in five bands (B, V, g, r, i).

You can display UCAC4, with data extracted either straight from the DVDs
or by putting it on your hard drive, by using the current Guide update (the
one available at

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

The procedure is basically the same procedure as for UCAC3:

http://www.projectpluto.com/update8e.htm#ucac3_hd_dvd

(except, of course, one should type 'UCAC4_PATH' instead of 'UCAC3_PATH'!)

-- Bill