495[vsx-dis] UCAC3 identifier format.
- Sep 20, 2009Sebastian,
>>>>>>>>>>>>>>>>>>Just to tell submitters that the official format for the recently released UCAC3 catalog (see
3UCAC FFF-NNNNNN instead of UCAC2 NNNNNNNN as in the UCAC2 catalog.
It will surely be a source of confusion.
This seems to contradict what is in the UCAC3 README file:
>>>>>>>>>>>>>>>>>>>>>Official UCAC3 star ID numbers should be utilized for identification purposes and for communication with the UCAC team. The main
identifier is the running star number in the CCD mean position data (MPOS number) which is provided on the UCAC3 individual star
records as the last 4-byte integer item. This number spans the range of 3 to 140051297 but includes gaps for stars which did not
make it into the release. MPOS numbers over 140 million identify high proper motion stars, which have been handled differently in
the pipeline and were merged at a later stage into the release.
Alternatively, a unique running star ID number without any gaps can be generated on the fly, counting stars along zones from south
to north and along RA within each zone, similarly to what was recommended for UCAC2.
ID = n0 + running star number in zone z
where z is zone number where the star in question is located (1 to 360; zone 1: -90 to -89.5 decl., ...), n0 is the largest star ID
number of the previous zone and ID is this official UCAC3 star ID number. A table is provided listing some statistics of zones,
which include this n0 number.
If needed, this 9-digit star ID number should be given in connection with the IAU sanctioned acronym of this project and this data
release number, such as "3UCAC100200300". The star ID number runs from 000000001 to 100766420. Leading zeros are to be used to fill
9 digits in the star name.
>>>>>>>>>>>>>>>>>>>>>I find no reference in the README to the 3UCAC NNN-XXXXXXX format. I may have just
Note also that the largest number given on the SIMBAD page (N=100765502) does not
agree with the largest number given in the README (N = 100766420).
You're right: it truly is a source of confusion.
Brian D. Warner
Palmer Divide Observatory
Collaborative Asteroid Lightcurve Link
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