Accession Number : ADA519276


Title :   UCAC3: Astrometric Reductions


Descriptive Note : Journal article


Corporate Author : NAVAL OBSERVATORY WASHINGTON DC


Personal Author(s) : Finch, Charlie T ; Zacharias, Norbert ; Wycoff, Gary L


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a519276.pdf


Report Date : Jun 2010


Pagination or Media Count : 9


Abstract : Presented here are the details of the astrometric reductions from the x, y data to mean right ascension (R.A.), declination (decl.) coordinates of the third U.S. Naval Observatory CCD Astrograph Catalog (UCAC3). For these new reductions we used over 216,000 CCD exposures. The Two-Micron All-Sky Survey (2MASS) data are used extensively to probe for coordinate and coma-like systematic errors in UCAC data mainly caused by the poor charge transfer efficiency of the 4K CCD. Errors up to about 200 mas have been corrected using complex look-up tables handling multiple dependences derived from the residuals. Similarly, field distortions and sub-pixel phase errors have also been evaluated using the residuals with respect to 2MASS. The overall magnitude equation is derived from UCAC calibration field observations alone, independent of external catalogs. Systematic errors of positions at the UCAC observing epoch as presented in UCAC3 are better corrected than in the previous catalogs for most stars. The Tycho-2 catalog is used to obtain final positions on the International Celestial Reference Frame. Residuals of the Tycho-2 reference stars show a small magnitude equation (depending on declination zone) that might be inherent in the Tycho-2 catalog.


Descriptors :   *ASTRONOMY , EFFICIENCY , REDUCTION , ERRORS , CHARGE TRANSFER , STARS , MEAN , HANDLING , CATALOGS , DISTORTION , REPRINTS , CALIBRATION


Subject Categories : Astronomy


Distribution Statement : APPROVED FOR PUBLIC RELEASE