アテン群
In 1973, Caltech astronomers Eleanor Helin and Gene Shoemaker began an observing program to search out and track previously unknown near-Earth asteroid, the Planet-Crossing Asteroid Survey (PCAS), a photographic plate survey that began on the Palomar 18" Schmidt telescope. Although primarily employed by the supernova survey to observe on the 48" Schmidt, Kowal provided "crucial observations" of particularly faint asteroids for the PCAS program with the larger telescope. His asteroid discoveries and co-discoveries include the notable asteroids Aten asteroid 2340 Hathor; the Apollo asteroids 1981 Midas, 2063 Bacchus, 2102 Tantalus and (5660) 1974 MA; the Amor asteroids (4596) 1981 QB and (4688) 1980 WF; and the Trojan asteroids 2241 Alcathous and 2594 Acamas. PCAS later moved to the 48" Schmidt, and ran in total for nearly 25 years, until June 1995.