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 of the main asteroid belt, and its long-term perturbations on the orbits of many solar system objects are important. For this rea- son, a very good knowledge of this mass is necessary. Although many determinations of the mass of Ceres have been made un- til now, the uncertainty remaining on its value is yet too high. A determination of the mass of Ceres, based on its gravita- tional 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 observations. Other accurate observations, recently made with the CCD meridian circles of Bordeaux and Valinhos (near S˜ ao Paulo, Brazil) observatories, were also included. The value ob- tained for the mass of Ceres, (4:759 0:023) 10 10 M ,i s in good agreement with most recent results obtained by the other authors, and is a more precise value of this mass. In particular, this result shows that the value of the mass of Ceres recom- mended by IAU should be decreased by nearly5%.