Named in honor of Hans F. Elsässer (1929– ), professor of astronomy at Heidelberg University and since 1968 first director of the Max-Planck-Institut für Astronomie. During 1962–1975 he was also director of the Heidelberg Observatory at Königstuhl. A scientific member of the Max-Planck-Gesellschaft, Elsässer was a founder of MPIA in Heidelberg and its associated observatory at Calar Alto. He has made important contributions to the study of interplanetary matter and the zodiacal light, the optics of the earth’s atmosphere, the structure of the Galaxy and the Magellanic Clouds and star formation. He was deeply concerned with the design and establishment of large telescopes and their auxiliary instrumentation at Calar Alto. Elsässer served as president of the IAU Commission 21 during 1970–1973. His many honors include membership in the scientific academies of Austria, Halle (Leopoldina) and... _ _.