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Observation of small solar system objects with spacewatch

Published online by Cambridge University Press:  25 May 2016

James V. Scotti  and
Robert Jedicke
James V. Scotti
Affiliation:
Lunar and Planetary Laboratory The University of Arizona Tucson, AZ, 85721 USA
Robert Jedicke
Affiliation:
Lunar and Planetary Laboratory The University of Arizona Tucson, AZ, 85721 USA

Abstract

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Since beginning an automated full-time survey for Near-Earth objects in September 1990, the Spacewatch project has discovered 95 new Near-Earth asteroids (NEAs), 3 new comets, and 3 new Centaur asteroids. Spacewatch typically identifies about 2000 main-belt asteroids each lunation while covering about 150 square degrees to a limiting magnitude of Vlim ∼ 20.9. We report automatically measured astrometric asteroid detections to the Minor Planet Center where known and multiply detected objects are identified. NEAs and other interesting objects are identified by their angular rates of motion near opposition at the time of discovery and are scheduled for astrometric follow-up on subsequent nights. Objects with exceptionally high rates of motion, called very fast moving objects, have been detected in near real-time by the observer and followed for several hours to several days. These objects are the smallest yet detected outside the Earth's atmosphere. Careful analysis of their discovery rates and orbits have indicated an enhancement of their magnitude-frequency distribution over that anticipated before the Spacewatch survey began – of about a factor of 40 for objects near absolute magnitude H ∼ 29 (Rabinowitz, 1993; 1994). A subset of these small objects which have almost circular orbits and perihelia near the orbit of Earth have been recognized as having significantly different orbits from those of the previously known NEAs (Rabinowitz et al., 1993). Their origin is still under debate, with possible sources including Earth or Lunar impact ejecta, Earth-Sun Trojans, or more complicated secular resonance interactions of NEA orbits with the giant planets combined with stochastic perturbational encounters with the inner planets (Bottke, 1994; N.W. Harris, 1995, personal communication). The large volume of asteroid detections allows magnitude–frequency studies of the detected main-belt asteroids and Jupiter Trojans. New discoveries of Comets and Centaur asteroids (whose orbits cross those of the outer planets) may allow studies of their magnitude–frequency distributions as well.

Type
Part X - Solar System Astrometry
Information
Symposium - International Astronomical Union , Volume 172: Dynamics, Ephemerides and Astrometry of the Solar System , 1996 , pp. 389 - 398
Copyright
Copyright © Kluwer 1996 

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