NOAO > Observing Info > Approved Programs > 2004B-0009
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NOAO > Observing Info > Approved Programs > 2004B-0009 |
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PI: Norbert Zacharias, USNO, nz@usno.navy.mil
Address: AD, 3450 Mass. Ave. NW, Washington, DC 20392, USA
CoI: Marion I. Zacharias, Univ. Space Research Ass. (USRA), USNO
CoI: Theodore J. Rafferty, U.S. Naval Observatory (USNO)
Title: Extragalactic reference frame link of the UCAC project
Abstract:
In January 1998 the US Naval Observatory CCD Astrograph (UCAC)
project, a high accuracy, high density, astrometric survey, was started
at CTIO. Observations of the southern hemisphere were completed and the
instrument relocated to Flagstaff, AZ, in October 2001. Full sky
coverage is expected by mid 2004. The second data release (UCAC2) was
published in July 2003. The 2--fold overlap pattern and block
adjustment techniques will allow for a strong link to extragalactic
reference frame sources utilizing deep CCD frames obtained with the CTIO
0.9m, KPNO 2.1m and the KPNO WIYN 0.9m telescopes.
With a small epoch difference between the deep and the astrograph
observations and a total of about 500 sources, an unprecedented accuracy
of the optical--radio reference frame link can be achieved. The
rotation of the Hipparcos system with respect to the International
Celestial Reference System (ICRS) will be determined by a factor of 2
more precisely than is currently known. Absolute position differences
in the radio--optical centers of emission for individual sources on the
10 mas level will be derived. Outliers will indicate astrophysically
interesting sources. The maintenance of a high accuracy radio--optical
reference frame link is important for current and future high resolution
imaging in all wavelengths, providing absolute positions (in an inertial
frame) on the 10 mas level at any location in the sky. To our
knowledge, this is the only major project in this area of research.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2004B-0009 |
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