Named in honor of Gart Westerhout, radio astronomer, on the occasion of his retirement as scientific director of the U.S. Naval Observatory. Westerhout developed the astronomy program at the University of Maryland into one of the best in the U.S. At the Naval Observatory, his incisive leadership and pioneering work in interferometric astrometry, including development of the first radio interferometer dedicated to astrometry, led to substantial advances in precise position, motion and time determination. (M 22830) _ _.