511 Davida
Davida (minor planet designation: 511 Davida) is a large C-type asteroid. It is one of the largest asteroids; approximately tied for 7th place, to within measurement uncertainties, and the 5th or 6th most massive. It was discovered by R. S. Dugan in 1903. Davida is named after David Peck Todd, an astronomy professor at Amherst College. Physical characteristics Davida is approximately 270–310 km in diameter and comprises an estimated 1.5% of the total mass of the asteroid belt. It is a C-type asteroid, which means that it is dark in colouring with a carbonaceous chondrite composition. From 2002 to 2007, astronomers at the Keck Observatory used the Keck II telescope, which is fitted with adaptive optics, to photograph Davida. The asteroid is not a dwarf planet: there are at least two promontories and at least one flat facet with 15-km deviations from a best-fit ellipsoid. The facet is presumably a 150-km global-scale crater like the ones seen on 253 Mathilde. Conrad et al. (2007) show that craters of this size "can be expected from the impactor size distribution, without likelihood of catastrophic disruption of Davida." Mass In 2001, Michalak estimated Davida to have a mass of () kg. In 2007,