AAS 197, January 2001
Session 31. Solar System and The Sun
Oral, Monday, January 8, 2001, 1:30-3:00pm, Sunrise

## [31.03] The Outer Edge of the Solar System

R.L. Allen, G.M. Bernstein (U. Mich), R. Malhotra (LPI)

In 1998 and 1999, we surveyed for Kuiper Belt Objects (KBOs) in 6 fields of the ecliptic (total sky area 1.3 deg2) to limiting magnitudes between R=24.9 and R=25.9. This is deep enough to detect KBOs of diameter \gtrsim 160~km at a distance of 65~AU. We detected 24 objects. None of these objects, however, is beyond 53~AU. Our survey places a 95% CL upper limit of \Sigma < 5\,{\rm deg}-2 on the surface density of KBOs larger than ~60~km beyond 55~AU. This can be compared to the surface density of ~\,{\rm deg}-2 of \ge160~km KBOs at distances 30--50~AU determined from this survey and previous shallower surveys. The mean volume density of D>160~km KBOs in the 55--65~AU region is, at >95% confidence, less than the mean density in the 30--50~AU region, and at most \twothirds\ of the mean density from 40--50~AU. Thus, a substantial density increase beyond 50~AU is excluded in this model-independent estimate. We present further survey results, including a luminosity function and KBO radial distribution model. This Kuiper Belt survey is funded by grants from NASA Planetary Astronomy and the National Science Foundation.