A Preliminary Look at Hungarias and Phocaeas Discovered by NEAT

K. J. Lawrence, E. F. Helin, D. L. Rabinowitz, S. H. Pravdo (JPL/CalTech)

With over 10,000 asteroid detections, the Near-Earth Asteroid Tracking (NEAT) project is beginning to develop a sufficient quantity of data such that asteroid families and orbital distributions can be examined. One area of particular interest is the Hungaria and Phocaea region of phase space. Their numbers have increased dramatically over the past decade primarily due to systematic asteroid search programs.

Early review of the orbital elements, determined by the Minor Planet Center (MPC), show a substantial number of Hungarias and Phocaeas (12 and 13, respectively) discovered by NEAT. Of particular interest is the 1:1 ratio of Phocaeas to Hungarias within this data. This is consistent with the photographic PCAS data reported by Helin and Roman (1989). However, as of December 1996, the Bigelow Sky Survey (BSS) has reported a 2:1 discovery ratio during their dedicated search for high inclination objects. Although, the BSS is concentrated on higher ecliptic latitudes perhaps a more suitable comparison can be made with the Palomar-Leiden (P-L) Survey which concentrated their observations on the ecliptic as NEAT does. It is somewhat curious that the P-L Survey found 9 Hungarias and no Phocaeas. Details of these results, along with the size and magnitude distributions, will be discussed.

Related abstract: Helin, E., et al.,.1997 DPS