DDA2001, April2001
Session 4. Posters
Monday, 8:00pm

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[4.09] Solar System Astrometry at McDonald Observatory: Progress Report

J.G. Ries, R.L. Ricklefs, P.J. Shelus, E.S. Barker (Dept. of Astronomy, The Univ. of Texas at Austin)

The McDonald astrometry group has been involved in solar system positional observations since the early 1970ís. It began as a photographic project but is now CCD based (Whipple et al, 1996). Recently, we focused our observations on Near-Earth Objects (NEOs). Our main goal is to confirm newly discovered objects and follow-up known, but under-observed, objects. This is part of NASA's mission to discover and catalogue 90 percent of NEOs larger than 1 km by the end of this decade. We wish to understand the physical nature of these objects and characterize the hazard they pose to Earth.

The prime focus instrument on the 0.76m telescope uses a 2048x2048 chip with 15 mm pixel size resulting in a 90 arcsec/mm plate scale. The limiting magnitude is mR~22, using a 15-min exposure. This allows us to follow-up virtually any object discovered by the various NEO search teams.

Although the CCD-based set up has not changed, the measurement and reduction software have evolved dramatically. Our emphasis is now on automation (Bertin and Arnouts., 1996) and we are working to produce a generalized, user-friendly, real-time astrometry package. Personal equation has been eliminated and we have switched from the ST/GS to the USNO-A02 catalog. Additional improvements will include locating and measuring all known minor planets on a frame, as well as searching for unknown objects on each frame. We expanded our observational efforts to perform relative photometry on the targets. The preliminary results will be presented at the meeting.

This research is funded by NASA NEO Program grants NAG5-6863 and NAG5-10183.

Bertin E., Arnouts S., 1996, A&AS, 117-393.

Whipple A. L. et al., 1996, AJ, 316-323.


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