Ivantsov A. Determination of masses of large asteroids from the ground-based positional observations

The thesis is devoted to mass determinations of the large asteroids by a dynamical method. In order to achieve this goal, the catalog of 622 asteroid positions linked to the ICRS system was compiled from observations made in Nikolaev during the period of 2000-2005. The catalog contains the positions of 24 asteroids down to 13 magnitude with the accuracy of 0.25" for a single determination. 2563 positions of 39 asteroids were also obtained with the Russian-Turkish telescope RTT150 from 2004 tіll 2005. The positions were determined in the ICRS system with the accuracy of 0.07" for a single determination. The author developed a software for representation of the dynamical model of asteroid motions. The model is based on DE405 ephemerides. Application of the model to the determination of the main-belt asteroid positions shows that the error in the position is 35 km in comparison with the HORIZONS system for 50 years of integration. This is equivalent to the error of 0.03" in spherical coordinates. New masses of 21 asteroids were determined by the dynamical method. Masses of asteroids Bellona (28) and Ate (111) were determined by the dynamical method for the fist time. Mass of asteroid De Sitter (1686) is also determined for the first time.