Physical Studies of Near-Earth Asteroids

Abstract

A new, long-term project has been started at the Institute of Panetary Exploration of th DLR in Berlin-Adlershof which is aimed to derive physical properties of Near-Earth Asteroids(NEA). We plan to monitor many of these newly discovered bodeies as targets of opportunity, and gradually will build up a data base which will contain important information, valuable for both cosmogonic reasons and for future space missions to NEA. From time-resolved photometry we obtain lightcurves, which allow the determination of the rotation period, and are indicative of the asteroid shape. Lightcurves from different apparitions can be used to determine the orientation of the spin axis and sense of rotation. Using the CCD camera systems developed at our institute, attaached to various telescopes at La Silla (ESO), Chile, and Kvistaberg, Sweden, we obtained differential photometry of six NEA: (1981) Midas, (2062) Aten, (5653) WD5, 1980 AA, 1993 BX3 and 1993 MF. For some of the asteroids accurate astrometric positions have been determined, using the photometric CCD frames and HST Guide Star Catalogue as a reference star system. These data are important to improve the orbit and secure future recovery. Here we present results on the derived rotation periods and lightcurve amplitudes for all six NEA.