Hiroki Kosai
Japanese astronomer (1933–2026)
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Hiroki Kosai (香西 洋樹, Kōsai Hiroki; 8 February 1933 – 26 March 2026) was a Japanese astronomer with the Kiso Observatory. He is best known for helping to popularize astronomy in Japan and for his observations of comets and asteroids, most notably with his co-discovery of the comet 1976 XVI.[2] He is credited by the Minor Planet Center (MPC) with the discovery of nearly 100 asteroids.[1]
Born8 February 1933
Died26 March 2026 (aged 93)
KnownforHelping to popularize astronomy in Japan
FieldsAstronomy
Hiroki Kosai | |
|---|---|
香西 洋樹 | |
| Born | 8 February 1933 |
| Died | 26 March 2026 (aged 93) |
| Known for | Helping to popularize astronomy in Japan |
| Scientific career | |
| Fields | Astronomy |
| Workplaces | Tokyo Astronomical Observatory |
| see § List of discovered minor planets |
Kosai died on 26 March 2026, at the age of 93.[3]
Awards and honors
Asteroid 3370 Kohsai, discovered by Karl Reinmuth at Heidelberg Observatory in 1930, is named in his honor.[4] The official naming citation was published by the MPC on 14 April 1987 (M.P.C. 11750).[5]
List of discovered minor planets
Hiroki Kosai discovered several asteroids, all in collaboration with A Kiichirō Furukawa and B Goro Sasaki:
| 2271 Kiso | 22 October 1976 | list[A] |
| 2330 Ontake | 18 February 1977 | list[A] |
| 2470 Agematsu | 22 October 1976 | list[A] |
| 2924 Mitake-mura | 18 February 1977 | list[A] |
| 2960 Ohtaki | 18 February 1977 | list[A] |
| 3111 Misuzu | 19 February 1977 | list[A] |
| 3249 Musashino | 18 February 1977 | list[A] |
| 3291 Dunlap | 14 November 1982 | list[A] |
| 3319 Kibi | 12 March 1977 | list[A] |
| 3320 Namba | 14 November 1982 | list[A] |
| 3391 Sinon | 18 February 1977 | list[A] |
| 3392 Setouchi | 17 December 1979 | list[B] |
| 3607 Naniwa | 18 February 1977 | list[A] |
| 3878 Jyoumon | 14 November 1982 | list[A] |
| 4072 Yayoi | 30 October 1981 | list[A] |
| 4077 Asuka | 13 December 1982 | list[A] |
| 4186 Tamashima | 18 February 1977 | list[A] |
| 4272 Entsuji | 12 March 1977 | list[A] |
| 4526 Konko | 22 May 1982 | list[A] |
| 4812 Hakuhou | 18 February 1977 | list[A] |
| 4855 Tenpyou | 14 November 1982 | list[A] |
| 4890 Shikanosima | 14 November 1982 | list[A] |
| 4929 Yamatai | 13 December 1982 | list[A] |
| 4963 Kanroku | 18 February 1977 | list[A] |
| 5017 Tenchi | 18 February 1977 | list[A] |
| 5018 Tenmu | 19 February 1977 | list[A] |
| 5082 Nihonsyoki | 18 February 1977 | list[A] |
| 5454 Kojiki | 12 March 1977 | list[A] |
| 5466 Makibi | 30 November 1986 | list[A] |
| 5541 Seimei | 22 October 1976 | list[A] |
| 6031 Ryokan | 26 January 1982 | list[A] |
| 6218 Mizushima | 12 March 1977 | list[A] |
| 6818 Sessyu | 11 March 1983 | list[A] |
| 6846 Kansazan | 22 October 1976 | list[A] |
| 7104 Manyousyu | 18 February 1977 | list[A] |
| 7105 Yousyozan | 18 February 1977 | list[A] |
| 7562 Kagiroino-Oka | 30 November 1986 | list[A] |
| 7627 Wakenokiyomaro | 18 February 1977 | list[A] |
| 7634 Shizutani-Kou | 14 November 1982 | list[A] |
| 7991 Kaguyahime | 30 October 1981 | list[A] |
| 8133 Takanochoei | 18 February 1977 | list[A] |
| 8144 Hiragagennai | 14 November 1982 | list[A] |
| 9147 Kourakuen | 18 February 1977 | list[A] |
| 9153 Chikurinji | 30 October 1981 | list[A] |
| 9293 Kamogata | 13 December 1982 | list[A] |
| 9719 Yakage | 18 February 1977 | list[A] |
| 10006 Sessai | 22 October 1976 | list[A] |
| 10008 Raisanyo | 18 February 1977 | list[A] |
| 10009 Hirosetanso | 12 March 1977 | list[A] |
| 10453 Banzan | 18 February 1977 | list[A] |
| 11254 Konkohekisui | 18 February 1977 | list[A] |
| 11255 Fujiiekio | 18 February 1977 | list[A] |
| 11442 Seijin-Sanso | 22 October 1976 | list[A] |
| 11827 Wasyuzan | 14 November 1982 | list[A] |
| 12186 Mitukurigen | 12 March 1977 | list[A] |
| 12221 Ogatakoan | 14 November 1982 | list[A] |
| 12682 Kawada | 14 November 1982 | list[A] |
| 14313 Dodaira | 22 October 1976 | list[A] |
| 14314 Tokigawa | 18 February 1977 | list[A] |
| 14315 Ogawamachi | 12 March 1977 | list[A] |
| 14316 Higashichichibu | 12 March 1977 | list[A] |
| 14338 Shibakoukan | 14 November 1982 | list[A] |
| 14795 Syoyou | 12 March 1977 | list[A] |
| 14820 Aizuyaichi | 14 November 1982 | list[A] |
| 14821 Motaeno | 14 November 1982 | list[A] |
| 15202 Yamada-Houkoku | 12 March 1977 | list[A] |
| 15671 Suzannedébarbat | 12 March 1977 | list[A] |
| 15672 Sato-Norio | 12 March 1977 | list[A] |
| 16357 Risanpei | 22 October 1976 | list[A] |
| 18289 Yokoyamakoichi | 22 October 1976 | list[A] |
| 18290 Sumiyoshi | 18 February 1977 | list[A] |
| 18291 Wani | 18 February 1977 | list[A] |
| 18322 Korokan | 14 November 1982 | list[A] |
| 19083 Mizuki | 18 February 1977 | list[A] |
| (19917) 1977 EE8 | 12 March 1977 | list[A] |
| 19953 Takeo | 14 November 1982 | list[A] |
| 19954 Shigeyoshi | 14 November 1982 | list[A] |
| 20962 Michizane | 12 March 1977 | list[A] |
| 22277 Hirado | 14 November 1982 | list[A] |
| 24640 Omiwa | 13 December 1982 | list[A] |
| 26794 Yukioniimi | 18 February 1977 | list[A] |
| 26806 Kushiike | 22 May 1982 | list[A] |
| (26808) 1982 VB4 | 14 November 1982 | list[A] |
| 34995 Dainihonshi | 18 February 1977 | list[A] |
| 34996 Mitokoumon | 18 February 1977 | list[A] |
| (37529) 1977 EL8 | 12 March 1977 | list[A] |
| (43753) 1982 VN3 | 14 November 1982 | list[A] |
| (48408) 1982 VN2 | 14 November 1982 | list[A] |
| 52260 Ureshino | 22 May 1982 | list[A] |
| 52261 Izumishikibu | 14 November 1982 | list[A] |
| (65635) 1977 EA8 | 12 March 1977 | list[A] |
| (73639) 1977 EL7 | 12 March 1977 | list[A] |
| (164616) 1986 WV8 | 30 November 1986 | list[A] |
| Co-discovery made with: A K. Furukawa B G. Sasaki | ||
|---|---|---|