From
http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac " UCAC3 official star numbers While the MPOS number (last column on each data record) mainly provides a means to identify known high proper motion stars, the primary star identification number should look like: 3UCzzz-nnnnnn The "3UC" is constant and indicates the UCAC3 catalog. The 3 digit "zzz" number is the zone the star is in, followed by a dash and a 6 digit number which is the record number of the star on that zone. Thus the official designation of the star 42 in zone 7 would be3UC007-000042. " It would seem the issue is settled. Sander John Mahony wrote: > > > There's been much discussion on MPML about UCAC3, and I recall > specifically a discussion about some confusion about ID numbers. > Unfortunately since the yahoogroups message search feature has been > broken for over 6 months now, I can't seem to find it, but I'll keep > looking. I did find one paragraph that might be useful, however: > > ---------------------------------------------------------- > "A final bit of information that is appropriate to share, as it is not > something > most will have > expected. The raw UCAC data at USNO is sorted entirely by declination. > RA is not > used in any way in > the sort, so that sequentially numbered stars can have RA's differing > by up to > +/-12hrs in RA. The > MPOS number (field 37 of the UCAC3 record) is the sequential number > allocated to > the stars in the > raw data on the basis of this sort (and there are about 140 million > stars in > this dataset, compared > to the 100 million in UCAC3). The data is placed into the declination > bands and > sorted by RA > _solely_ for the purpose of creating the public catalogue." > --------------------------------------------- > > But I don't think that was part of the specific discussion about ID > numbers. > > Also, Bill Grey (Project Pluto/ Guide8) has some source code available > for accessing the catalog: > <http://www.projectpluto.com/ucac3.htm > <http://www.projectpluto.com/ucac3.htm>> > > I'm not a programmer so I didn't look very close there at first, but > now I see he also has some info on the designation confusion (see the > last few paragraphs). > > -John > > > > - >
