INVESTIGATIONS OF OSCILLATIONS IN THE BRIGHTNESS OF ASTEROID-1620 GEOGRAPHER DURING ITS APPROACH TO THE EARTH IN 1994

Comprehensive investigations were conducted of Asteroid 1620 Geographe r during its approach to the Earth in 1994. A frequency analysis of fi ne photometric effects and oscillations in its brightness was performe d using data from a catalog of photometric observations of asteroids. This analysis confirms the monolithic nature of the very elongated bod y of the asteroid. In addition to the known rotation period of the ast eroid, periods of 0(d).8 and 2(d).8 are detected, as well as multiples of these periods. The observed periodicity suggests that the first of these periods is associated with free precession of the rotation axis of the asteroid, while the second is due to forced precession with pr ecession angle 3 degrees +/- 1 degrees. The free precession could have arisen either during the formation of the asteroid or during a collis ion with another body. The presence of forced precession and the fact that Geographer is associated with a meteor shower is consistent with the possible existence of modest-sized companions.