1942 RQ. Discovered 1942 Sept. 8 by L. Oterma at Turku.
Named in memory of Ivan Leslie Thomsen (1910–1969), director of the Carter Observatory, Wellington, from 1945 until his appointment as astronomer-in-charge of the Mount John Observatory only two months before his death. He was an enthusiastic coordinator of astronomy in New Zealand, and his efforts eventually led to the minor-planet observing program with the Carter Observatory 41-cm reflector. It was the 1977 rediscovery at the Carter Observatory that allowed this minor planet to be numbered. (M 4421)