LIGHTCURVES AND ROTATIONAL PERIODS OF 9 MAIN BELT ASTEROIDS

In this paper we present the results, obtained from September 1990 to October 1991, of a collaborative program between the Torino Astronomic al Observatory and the Astronomy Institute of Catania University, whic h started 3 years ago, devoted to the determination of the rotational properties of the asteroids, to enlarging the available data set, and to obtaining bias-free photoelectric observations of small objects. We have determined reliable synodic rotational periods for the asteroids 122 Gerda (P = 10.332h +/- 0.004h), 137 Meliboea (P = 15.28h +/- 0.02 h), 160 Una (p = 5.61h +/- 0.01h), 168 Sybilla (P = 23.82h +/- 0.04h), 377 Campania (P = 8.507h +/- 0.003h), 454 Mathesis (P = 7.75h +/- 0.0 25h), 550 Senta (P = 20.555h +/- 0.01h), and 937 Bethgea (P = 8.356h /-0.006). For 500 Selinur we obtained an estimate of about 9h of the p ossible spin period. (C) 1994 Academic Press, Inc.