Tsutomu Seki (関 勉, Seki Tsutomu, born November 3, 1930) is a Japanese amateur astronomer and discoverer of minor planets and comets, born in Kōchi, Japan.
Tsutomu Seki is the Director of the Geisei Observatory in Kōchi, and in charge of the Comet Section of the Oriental Astronomical Association.
Many of his discoveries are named after famous sites in Kōchi, such as Harimaya-bashi, Ryōma (after Sakamoto Ryōma), Katsurahama beach, and Kagami-gawa.
Asteroid 3426 Seki, discovered by Karl Reinmuth at the Heidelberg Observatory in 1932, was named in his honor.
[2] The official naming citation was published by the Minor Planet Center on 16 December 1986 (M.P.C.