The brightness variations of asteroid 216 Kleopatra

Orbits with varying degrees of accuracy have been determined for over 2500 asteroids, since the first asteroid was discovered by Piazzi in 1801. Albedos range from a low 2 percent (carbonaceous surfaces) to a high 48 percent (siliceous surfaces). Of the asteroids with known light curves, 216 Kleopatra is one which displays considerable variations in brightness within several hours. Scaltriti and Zappala (1977) detected an amplitude of 0.4 mag. More recently, Tholen (1980) found an amplitude of 1.35 mag. Observations conducted in connection with the present investigation indicate an amplitude of 0.70 mag. Kleopatra was observed photoelectrically on the UT dates 15 and 30 September and 1 and 2 October, 1980. The observations were made with a 15-inch reflecting telescope. Data regarding the light curve amplitude, time, phase angle, and ecliptic longitude are presented in a table. The values indicate that the amplitude is a function of solar phase angle.