Hiroki Kosai (香西 洋樹, Kōsai Hiroki, born 8 February 1933) is a Japanese astronomer with the Kiso Observatory.
[2] He is credited by the Minor Planet Center (MPC) with the discovery of nearly 100 asteroids.
[1] Asteroid 3370 Kohsai, discovered by Karl Reinmuth at Heidelberg Observatory in 1930, is named in his honor.
[3] The official naming citation was published by the MPC on 14 April 1987 (M.P.C.
[4] Hiroki Kosai discovered several asteroids, all in collaboration with A Kiichirō Furukawa and B Goro Sasaki: