The polarization curve and the absolute diameter of Vesta

A new photoelectric polarization curve for Vesta is presented. It is incompatible with Lyot's photographic curve which appears to be inaccurate. The new polarization curve indicates that the reflectivity of Vesta is higher than that of the Moon, and a pre;iminary value of 0.25 ± 0.07 for the reflectivity in the V is suggested. This implies an absolute diameter of about 510 km, a value consistent with the diameter of Vesta calculated from its mass, assuming an achondritic composition.