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Radio-Optical Reference Frame Link Using the US Naval Observatory Astrograph and Deep CCD Imaging
Norbert Zacharias, Marion I. Zacharias
Between 1997 and 2004 several observing runs were conducted mainly with the CTIO 0.9 m to image ICRF counterparts (mostly QSOs) in order to determine accurate optical positions. Co…
The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
Norbert Zacharias, Charlie Finch, Terry Girard +4
The fourth United States Naval Observatory (USNO) CCD Astrograph Catalog, UCAC4 was released in August 2012 (double-sided DVD and CDS data center Vizier catalog I/322). It is the f…
The Third US Naval Observatory CCD Astrograph Catalog (UCAC3)
N. Zacharias, C. Finch, T. Girard +27
The third US Naval Observatory (USNO) CCD Astrograph Catalog, UCAC3 was released at the IAU General Assembly on 2009 August 10. It is the first all-sky release in this series and c…