USNO CCD Astrograph Catalog (UCAC)
Last update: 2010 Feb 22
UCAC is an astrometric, observational program, which started in February 1998 at CTIO. All sky observations were completed at the Naval Observatory's Flagstaff Station in May 2004, and data reduction was completed in July 2009. The final UCAC3 catalog will be released on August 10, 2009 at the meeting of IAU Commission 8, during the IAU General Assembly in Rio de Janero, Brazil. DVDs are in production and will be send to customers on
the UCAC2 distribution list, and those who already requested it.
The catalog is free of charge, although our resources are limited
and distribution of the double-sided DVD will take several weeks.
The 8 GB binary files will also be made available at CDS soon.
For more details, please see the readme_u3 file.
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 be of the form:
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.
- UCAC3 was released 2009 August 10 at the IAU General Assembly in Rio. DVDs are being shipped throughout the month of September to recipients on the distribution list (see the readme_u3 file.). The data are also available from the CDS.
- UCAC3 software development and testing for the pixel
re-reduction is now almost complete. The final
catalog release is currently scheduled for August 2009.
Position data from UCAC r14 for SN NGC 2403 field.
Please read the format explanations.
The observational program is complete. The last survey fields were taken successfully on 17/18 May 2004. A final all-sky plot is presented in the final monthly progress chart.
- The Bright Star Supplement (BSS) to UCAC2 is now available. It contains exactly 430,000 stars from Hipparcos and Tycho-2 data to fill in the sky area missed by UCAC2 plus the all sky bright stars not in UCAC2. The files can be obtained from (new location since mid 2006) anonymous ftp ad.usno.navy.mil, /users/nz/bss/ , please start with the "readme" file, which is also available here. A plot shows the sky distribution of all BSS stars.
- UCAC2: was released at the IAU GA
in Sydney. Over 1200 copies have been distributed so far.
The catalog introduction file (readme.txt) is available. It contains a detailed description of all files, formats and notes for the user.
Example data files (z001 to z007), as well as the unformatted index file (u2index.da) can be downloaded from our anonymous ftp server ad.usno.navy.mil/pub/nz .
The paper describing the UCAC2 was published in AJ, 127, 3043-3059 (May 2004) and a pre-print is also available from (astro-ph) as entry 0403060.
The UCAC2 is now available from
(Vizier, Strasbourg) as entry I/289.
A color plot shows the sky coverage of UCAC2.
UCAC2 CD-ROM files access code in C/C++ is now available from (Project Pluto).
- The history of other news notes
has been relocated to a separate page.
- The paper describing the UCAC2
is published in AJ, 127, 3043-3059 (May 2004)
and a pre-print is also available from
(astro-ph) as entry 0403060.
- Astrometric surveys in support of large telescopes,
Proc. SPIE Vol. 4836, p.279; Eds. J.A.Tyson, S.Wolff, 2002, Hawaii
- Sky and Telescope, July 2001, p.22 and p.65
- detailed UCAC1 description, AJ 120, 2131 (Oct.2000)
- UCAC1 versus Tycho-2 comparison, AJ 120, 1148 (Aug.2000)
- Hubble Deep Field - South link to Hipparcos
- The UCAC astrometric survey
(ADASS 1999, ASP Conf.Ser. 216, 427)
- Data structure and software...
(ADASS 1998, ASP Conf.Ser. 172, 345)
- 189th AAS meeting (poster paper)
- feasibility study, AJ, 113, 1925 (1997)