The Use of the 48-inch Schmidt Telescope for Selenodetic Observations

Abstract

Photographing the Moon against star-field backgrounds is recognized as a most useful technique for measuring the difference between universal and ephemeris times, determining various higher-order motions of the Earth and Moon, and investigating certain geodesic problems. Because simultaneous photographic observations of the Moon and stars might be effectively used with new reduction techniques developed by Kopal for determining lunar librations from star positions independent of reference to the lunar limb, Kopal recently requested that we investigate the feasibility of utilizing the 48-inch Palomar Schmidt as a moon-star camera. The Schmidt is rarely in use when the Moon is above the horizon and good supplementary use could be made of the instrument if it should prove adaptable for lunar work.