(9942) 1989 TM1 is a stony asteroid from the inner regions of the asteroid belt, approximately 4.5 kilometers in diameter. It was discovered on 8 October 1989, by Japanese astronomers Nobuhiro Kawasato and Tsutomu Hioki at Okutama Observatory (877), Japan. In October 2010, a rotational light-curve for this asteroid was obtained from photometric observations at the U.S. Palomar Transient Factory, California. It rendered a tentative rotation period of 3.0706±0.0004 hours with a brightness variation of 0.08 in magnitude (U=1).