THE MASS OF (1)CERES FROM ITS GRAVITATIONAL PERTURBATIONS ON THE ORBITS OF 9 ASTEROIDS

The mass of (1) Ceres is about half of the total mass 2. Method of the main asteroid belt, and its long-term perturbations on the orbits of many solar system objects are important. For this reason, a very good knowledge of this mass is necessary. Although many determinations of t he mass of Ceres have been made until now, the uncertainty remaining o n its value is yet too high. A determination of the mass of Ceres, bas ed on its gravitational perturbations on the orbits of 9 asteroids, is presented. All the available observations of the perturbed asteroids were used. In particular, for the asteroids observed by Hipparcos, the very accurate Hipparcos data were added to the ground-based observati ons. Other accurate observations, recently made with the CCD meridian circles of Bordeaux and Valinhos (near Sao Paulo, Brazil) observatorie s, were also included. The value obtained for the mass of Ceres, (4.75 9 +/- 0.023) 10(-10) M., is in good agreement with most recent results obtained by the other authors, and is a more precise value of this ma ss. In particular, this result shows that the value of the mass of Cer es recommended by IAU should be decreased by nearly 5%.