See <http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac> that seems to be the same info, right on USNO's website.
I found the lost discussion I mentioned earlier (it was on another group, for an asteroid astrometry software). Here it is, re-shuffled to top-down order, with names/addresses edited: > > From: "Bob" > > > > I received a copy of UCAC3 today from USNO. So apparently distribution > > is well underway. > "Dave" a écrit : > > > > That is good to know. > > > > Of course the real advantages of UCAC3 will not be available until > > software authors (such as > > Herbert) have changed their program so that it can read UCAC3. Until > > that occurs, you won't be able > > to 'use' the DVD unless you write your own programs to access the > > data. [In that context, I expect > > an announcement in the next few days concerning the manner in which > > UCAC3 stars are to be > > 'officially' identified - which is different to that set out in the > > Readme file.] > From: "Marc" > > Is the answer here : > http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac ? --- "Dave" wrote: > > As I indicated the other day, there has been an 'announcement about the > official star numbering for > stars in UCAC3. It is indeed on the UCAC3 web page (as linked below) in the > opening text. It states: > > ************ > 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 be 3UC007-000042. > ********** > > Users of Vizier will note that this numeration is now used there for UCAC3. > > Dave "Dave" is the same person who wrote the paragraph I copied earlier from MPML. I'm not sure how he knew that the new designation format would be different from the readme file. -John ----- Original Message ---- > From: Sander Pool <[email protected]> > To: [email protected] > Sent: Thursday, September 24, 2009 4:48:24 PM > Subject: Re: [skychart-discussion] UCAC3 identifier > > > Thanks John for forwarding that link. This is the crucial paragraph: > > " > > *New UCAC-3 designation scheme: *UCAC-3 had two designation schemes, but > a third has been settled upon: '3UC', followed by a zone number from 1 > (stars between declinations -90 to -89.5) to 360 (stars between decs > +89.5 to +90), followed by a six-digit number giving the order of that > star within that declination zone. For example, '3UC314-159265' would be > the 159265th star in zone 314 (the zone covering declinations +66.5 to +67). > > '3UC' was used because '3U' had been taken by another astronomical > catalogue. > " > > It doesn't really say who settled this. It would be nice to see a > confirmation from the USNO especially because it's not consistent with > UCAC2. > > 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: > > > > > > > > > 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 > > > > > > > > ----- Original Message ---- > > > From: Patrick Chevalley > > > > > > > From what I understand I already found tree different way to > > identify an UCAC3 > > > star :-( > > > We need to clarify this point before to build a search index. > > > > > > From the UCAC3 readme 3i) : > > http://ad.usno.navy.mil/ucac/readme_u3.html > > > > > 1- the last 4 bytes of the zone files contain the MPOS number. This > > number spans > > > the range of 3 to 140051297 > > > 2- ID = n0 + running star number in zone z "3UCAC100200300". n0 is > > the largest > > > star ID number of the previous zone. The star ID number runs from > > 000000001 to > > > 100766420. > > > > > > From Vizier Note (1): > > http://cdsarc.u-strasbg.fr/viz-bin/Cat?I/315#sRM3.1 > > > > > 3- 3UC"zzz-nnnnnnn", where zzz is the zone number and nnnnnn a > > 6-digit running > > > number in the zone. "3UC180-000007" > > > > > > Can someone with better english can clarify the UCAC3 readme 3i). it > > is quite > > > confuse for me. > > > > > > Also, do anyone know which identifier will be used the most > > frequently by people > > > using UCAC2 now? by IOTA? for SN chart? > > > > > > Patrick > > > > > > > > > > > > ------------------------------------ > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > ------------------------------------ > > Yahoo! Groups Links > > >
