Direct detection of a cometary nucleus with the Hubble Space Telescope.

Abstract

We report the unambiguous detection with the Planetary Camera of the Hubble Space Telescope of the nucleus of comet P/Faye 1991XXI during its last perihelion passage when it was at 0.6AU from the Earth. The high resolution of the HST allowed to discriminate the nucleus against the bright coma. The reduced V magnitude of the nucleus ranges between 15.5 and 15.9. Assuming a geometric albedo of 0.04, we found a rather spherical body with a mean radius of 2.68km.