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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.
The author(s) of this abstract have provided an email address for comments about the abstract: rhiannon@umich.edu