IAU logo

Densification of the Optical Reference Frame (Commission 8)



This site is devoted to projects of which members of the group should be aware. Feel free to contact Norbert Zacharias if you would like to see additional projects added to this site.

Projects underway or recently completed:

  • UCAC
    The U.S. Naval Observatory's CCD Astrograph was moved from CTIO to Flagstaff Arizona at the end of 2001 to continue observing the Northern Hemisphere sky. Global sky coverage was completed in May, 2004.

    The second data release, called UCAC2, includes the areas observed up to December 2002. The UCAC2 has 48 million stars, all with proper motions and 99.5% with 2MASS photometry. USNO has run out of the CDs (over 1000 were distributed), but the data are available via the CDS. A complete re-processing of the pixel data is in progress. The final relaase of UCAC (UCAC3) is expected in August 2009.

    Additional information on the UCAC project can be found at http://ad.usno.navy.mil/ucac. Point of contact for the UCAC project is Norbert Zacharias (nz at usno.navy.mil).

  • PMM Catalogs, USNO A and B
    The USNO Flagstaff Precision Measuring Machine (PMM) has provided measurements from several photographic surveys. Dave Monet (dgm at nofs.navy.mil) is the point of contact. Information on this project can be found http://ftp.nofs.navy.mil/projects/pmm.

    • - The USNO-A is now considered obsolete and is no longer supported.
    • - The USNO-B catalog is now public. See http://www.nofs.navy.mil/data/FchPix/.
    • - The merge of USNO-B and 2MASS is underway.
    • - Reductions of the measurements of the blue and yellow Lick/Yale plates from the NPM/SPM work are in progress.
    • - National Virtual Observatory access to PMM data products (catalogs and pixel data) is in the planning and initial development stages.

  • 2MASS
    The 2MASS project has completed mapping the entire sky in the IR realm. Although not strictly under the "Optical" as in the group's title, it does contain over 470 million point sources at positional accuracies of about 100 mas. Final data release was March 25, 2003. Additional information on this project and access to the data can be found http://pegasus.phast.umass.edu/2mass.html.

  • Southern Proper Motions, SPM 3.1
    The third installment of the SPM catalog is now available. Note that this does NOT supersede the SPM 2.0, as SPM 2.0 is more accurate (see below). Absolute proper motions, positions, and photographic B,V photometry are given for roughly 11 million objects, down to a magnitude of V=17.5. The Catalog covers an irregular area of 3700 square degrees, between the declinations of -20 and -45 degrees, but excluding the Galactic plane. All observations were made with the 50-cm double astrograph of Cesco Observatory in El Leoncito, Argentina.

    The catalog is based on full-plate scans using the USNO Precision Measuring Machine (PMM) and its image detection and centering software. Almost all SPM fields for which second-epoch plates are available have been included, excepting the Galactic plane. The proper-motion precision, for well-measured stars, is estimated to be 4 mas/yr.

    Unlike previous releases of the SPM Catalog, the proper motions are on the International Celestial Reference System by way of Hipparcos Catalog stars, and have an estimated systematic uncertainty of 0.4 mas/yr. More information can be obtained from Bill van Altena and the Yale Astrometry Group's Web site at http://www.astro.yale.edu/astrom/.

  • Southern Proper Motions, SPM 2.0
    The second installment of the SPM catalog is now available. The SPM Catalog 2.0 provides positions, absolute proper motions, and photographic BV photometry for over 320,000 stars and galaxies. All objects contained in the SPM 1.1 Catalog (the South Galactic Pole region) are also included in this version. The Catalog covers an area of ~3700 square degrees in an irregularly bounded band between declinations of -43 and -22 degrees, but excluding fields in the plane of the Milky Way. Stars cover the magnitude range 5 < V < 18.5. The standard errors for the best measured stars are as follows: 20 mas for positions in each coordinate; 2 mas/yr for absolute proper motions and 0.05 mag in B and V bandpasses. In addition to the Catalog, a list of CCD calibrating sequences in BV is provided, containing 7783 stars. The new feature of the Catalog is an extensive list of cross-identifications with external special catalogs which include all major astrometric catalogs and a large number of astrophysically interesting objects.

  • Carlsberg Meridian Telescope
    The fourteenth installment from the Carlsberg Meridian Telescope is now available (CMC14). It is an astrometric and photometric catalogue of 95.9 million stars in the red (r') magnitude range 9 to 17. This catalogue is the next release of the CMT CCD survey and covers the declination range -30° to +50°.
    The external accuracy has been estimated to be
    r' RA Dec Mag
    <13 34 33 25
    14 38 34 35
    15 52 41 70
    16 88 63 170
    where the above units are mas and millimag

    CMC14 has an overall completeness of 95-98%. The density of stars in the catalogue ranges from 500 to 13,000 stars per square degree. The catalogue can be found at: http://www.ast.cam.ac.uk/~dwe/SRF/cmc14.html. A DVD containing the data can be obtained if there is difficulty in obtaining the data over the Internet. Contact José Luis Muiños Haro (ppmu at roa.es) for further information.

  • Deep Astrometric Standards
    New, large imaging telescopes such as the Large Synoptic Survey Telescope (LSST) and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) have substantiated the need for deep and precise reference frames. A proposal to establish some selected deep astrometric standards has been made. These Deep Astrometric Standards (DAS) will go as faint as V=25. The original intent of the DAS is to enable a reliable geometric calibration of solid-state mosaic detectors in the focal plane of large telescopes, but it is recognized that they will make a substantial contribution to our understanding of stellar populations in the Milky Way. See Platais, Wyse, and Zacharias, 2006, PASP 118 107.

  • Tycho-2 Catalogues
    The Tycho-2 Double Star Catalogue was released February, 2002. This contains data on 105,259 components of multiple star systems. The Tycho-2 homepage can be found at http://www.astro.ku.dk/~erik/Tycho-2/

  • Shanghai Astronomical Observatory work
    Some of the projects of the Shanghai Astronomical Observatory can be found here. For additional details, please contact Shuhe Wang (shwang at center.shao.ac.cn).

  • Pulkovo work
    Densification of ICRS in the Optical by use of Old Pulkovo Observation Sets was discussed in a poster paper by Irina Kumkova (Institute of Applied Astronomy RAS), Vadim Bobylev (Pulkovo) and Nina Bronnikova (Pulkovo), presented at IAU Colloquium 180. The abstract is printed here.

  • Naval Observatory Merged Astrometric Database (NOMAD)
    The Naval Observatory Merged Astrometric Database (NOMAD) is a USNO project to allow users to retrieve the best currently available astrometric data for any star in the sky. It currently incorporates astrometry from Hipparcos, Tycho-2, UCAC2 and USNO-B1. It is supplemented with 2MASS photometry. Additional catalogs will be incorporated as time and availablility allow. See http://www.nofs.navy.mil/nomad/ for additional information.

Astrometric Satellite Projects:

  • GAIA
    GAIA, the European Space Agency's astrometric satellite mission, is progressing. It is designed to observe about one billion stars with accuracies from about 10 microarcseconds to ~200 microarcseconds, based primarily on magnitude. It is anticipated to launch prior to 2012. More information on the GAIA project can be found at http://www.esa.int/esaSC/120377_index_0_m.html.

    The Joint Milliarcsecond Pathfinder Survey (JMAPS) concept was developed at USNO. In 2008 this mission was funded by DoD. JMAPS is expected to launch in 2012 and will provide positions and parallaxes for millions of bright stars to 1 mas accuracy. Proper motions will also be derived. For the subset of Hipparcos stars the errors in proper motions will be less than 0.1 mas/yr.

  • DIVA
    The DIVA astrometric satellite is a German astrometric mission. It was cancelled in February 2003 due to financial concerns. News on the DIVA project can be found at http://www.ari.uni-heidelberg.de/diva/news.html.

Miscellaneous Items:

  • Astrographic Catalogue and Carte du Ciel
    The WG dealing with the plates of the Astrographic Catalogue and the Carte du Ciel is chaired by Beatrice Bucciarelli. A website can be found at http://www.to.astro.it/astrometry/AC_CdC/.

  • IAU General Assembly, Manchester
    At the IAU in Manchester, an informal discussion on star surveys was held. This, for the most part, dealt with zonal catalogs being observed by transit instruments. The meeting was organized by Dafydd Evans (dwe at ast.cam.ac.uk), who has kindly gathered most of the viewgraphs from the various speakers. Titles, presenters and viewgraphs can be found at http://www.ast.cam.ac.uk/~dwe/AstSurv/.