| U.S. Naval Observatory |
Astrometry Department |
The Radio Optical Reference Frame
Optical Image Database (OID)
Presented here are preliminary results of an ongoing program to
obtain precise optical positions of the RORF
sources. The radio frame, defined by the positions of selected
extragalactic radio sources, can now be established to an accuracy of
better than one milliarcsecond. This defines a frame that is more
accurate than the projected internal accuracy of the HIPPARCOS catalog
and far exceeds that of the Fifth Fundamental Catalog (FK5). Because
of the need to link these optical reference frames to the radio, it is
important to include in the radio catalog objects that are detectable
at both radio and optical wavelengths. In this way, the accuracy of
the optical catalogs can be improved, including the proper
motions.
Last modified: Wed Jun 13 09:43:40 EDT 2001
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