A Method To Measure The Geocentric Distance Of A Main-belt Asteroid Using Only Two Frames Of CCD Image In Each Two Nights

The main-belt asteroid(MBA)is a kind of important celestial body in the solar system,and most of these MBAs are faint.In general,the modern large telescope(8~10 m)was used for the observation of these faint MBAs.However,the time investment of this observation is very high.It usually needs 7-10 nights' observations to determine the distance of a MBA using the method of orbit fitting.Detailed analyses of their distance are confined to larger objects or use only rough statistical distances.North American scholars Heinze and Metchev proposed a novel method for calculating precise distances to the MBAs using only two nights of data from a single observatory.Thus the efficiency of distance determination of a MBA is greatly improved.This method uses the angular velocity component of the earth's rotation,so it was referred to as the rotational reflex velocity(RRV).However,the derivation of RRV described by Heinze and Metchev is not easily understood for astrometry.Moreover,some physical quantities used in their derivation are approximated,this approximation in turn causes a certain error of RRV distance.In this thesis,we re-derive the solution but use the knowledge of spherical astronomy,so it's easily understood by astrometrists.Our derivation is based on the premise that the geocentric angular velocity of an asteroid changes linearly with time,which is closer to the real situation.Therefore,a possible extra error of rotational reflex velocity,in some cases,is eliminated.In addition,a total of 193 frames of CCD images over four nights for 10 asteroids in a conventional stare mode taken with the 1 m telescope at Yunnan Observatory were used to test the improved solution and precise distances were evaluated.