Discovered Appeared Not observed Appeared before discovery Not observed before discovery Returns in the future
31P2028 Mar. 19 31P2019 July 6 31P2010 Sept.29 31P2002 Jan. 18 31P1994 Jan. 23 31P1987 Aug. 30 31P1981 Mar. 17 31P1974 Sept.12 31P1968 Mar. 14 31P1961 Sept. 5 31P1955 Feb. 27 31P1948 Aug. 23 31P1942 Feb. 13 31P/1934 X11935 Aug. 28 31P/1929 B11929 Mar. 23