Fundamental Thermal Emission Parameters of Main - Belt Asteroidsderived from Iso

In support for the ISO Mission it has been necessary to establish a set of asteroids as photometric standards for the photometric calibration of the instruments (M uller & Lagerros 1998). The new standards are described as rotating ellipsoids. Illumination geometry, heat transfer due to non-zero thermal inertia and surface structure/porosity are taken into account. The characteristic properties of this new thermophysical model (TPM) can be found in Here we apply the TPM to a set of ISO observations on (1) Ceres to derive its thermophysical properties. We determine the thermal inertia, the beaming function, caused by surface roughness and porosity, and the wavelength dependent emissivity. Since we are able to model the full thermal emission over the wavelengths range from 5 to 200m, we believe that our ndings represent fundamental thermal emission properties not only of (1) Ceres, but also of other Main-Belt asteroids.