NOAO > Observing Info > Approved Programs > 2001A-0058
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NOAO > Observing Info > Approved Programs > 2001A-0058 |
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PI: Norbert Zacharias, U.S. Naval Observatory, nz@pisces.usno.navy.mil
Address: 3450 Mass.~Ave.~N.W., Washington, DC 20392, USA
CoI: Theodore J. Rafferty, USNO
CoI: Marion I. Zacharias, Univ. Space Research Ass. (USRA) / 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 in
August 2000 and the instrument is scheduled to be re--located to
Flagstaff, AZ, in April 2001. Full sky coverage is expected by mid
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, and proposed KPNO
2.1m observations, to cover the northern hemisphere.
Assuming a small epoch difference between the 2.1m and the
astrograph observations for each of the about 300 fields to be observed
over 2 years, 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 its 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 > 2001A-0058 |
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