Submillimeter observations of the asteroid 10 Hygiea

The first successful ground-based observations of any asteroid at submillimeter wavelengths are reported. Observations of the asteroid 10 Hygiea at 370 and 770 micrometers are combined with observations in the near and thermal infrared (2.2, 10.6, and 21 micrometers) to study the thermal properties of Hygiea's regolith. The 'standard' (nonrotating) thermal model is consistent with the entire data set, although a rotating thermophysical model with a 'lunarlike' thermal inertia cannot be ruled out.