Named for Henry E. Holt, planetary geologist with the U.S. Geological Survey and Northern Arizona University. As a member of the Surveyor and Apollo scientific teams, he investigated the detailed geology and photometric properties of the lunar surface. Since retiring from the Geological Survey, he has been a principal participant in the Palomar Asteroid and Comet Survey and is the discoverer or codiscoverer of six comets and numerous asteroids, including (4581) Asclepius, the numbered asteroid that has made the closest approach to the earth. (M 17656) _ _.