is an amateur astronomer based in Yamagata, the capital city of

Yamagata Prefecture is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. It has a population of 1,005,926 (1 February 2025) and an area of 9,325 Square kilometre, km2 (3,600 Square mile, sq mi). Its neighbours are Akita Prefectu ...

in the

Tōhoku region The , Northeast region, , or consists of the northeastern portion of Honshu, the largest island of Japan. This traditional region consists of six prefectures (): Akita, Aomori, Fukushima, Iwate, Miyagi, and Yamagata. Tōhoku retains ...

of northern

Honshu , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...

island,

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. He is responsible for discovering many comets, and over 170

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

e.The Starwatcher: Amateur astronomer Koichi Itagaki is one of the most prolific supernova hunters of all time
Dennis Normile,

Science (journal) ''Science'' is the peer review, peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and h ...

, 2023-07-06

Early life

Itagaki had an early fascination with

lens A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...

es, and used them to burn paper with concentrated

sunlight Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...

. In 1963, the 19-year-old Japanese amateur Kaoru Ikeya created national headlines when he discovered a comet with his homemade telescope. Itagaki was thus encouraged and bought a telescope and, after completing highschool, discovered a comet himself at age 20. He joined his father's snack food company, Itagaki Peanuts, and rose in the company to be its CEO. At age 60, he retired, handing over the company to his sons.

Amateur Astronomy

Itagaki says he has spent the Yen equivalent of a modest home in his astronomy hobby. Initially, in around 2008, he leased some land just out of Yamagata, in the Zaō Mountains (蔵王連峰, Zaō Renpō) and eventually built four domes for , , and telescopes and a hut for the associated equipment. In 2015, he built an automated telescope site near

Okayama is the prefectural capital, capital Cities of Japan, city of Okayama Prefecture in the Chūgoku region of Japan. The Okayama metropolitan area, centered around the city, has the largest urban employment zone in the Chugoku region of western J ...

, in

Okayama Prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūgoku region of Honshu. Okayama Prefecture has a population of 1,826,059 (1 February 2025) and has a geographic area of 7,114 Square kilometre, km2 (2,746 sq mi). Okayama Prefecture ...

Chūgoku region The , also known as the region, is the westernmost region of Honshū, the largest island of Japan. It consists of the prefectures of Hiroshima, Okayama, Shimane, Tottori and Yamaguchi. As of the 2020 census, it has a population of 7,328,339 ...

of Honshu, around 700 kilometers to the southwest. In 2018, he built another remotely controlled telescope site on

Shikoku is the smallest of the List of islands of Japan#Main islands, four main islands of Japan. It is long and between at its widest. It has a population of 3.8 million, the least populated of Japan's four main islands. It is south of Honshu ...

island. The three sites allow him to have a variety of observations, and mostly to have one site not obscured by weather on any given night. As of mid-2023, Itagaki's most recent discovery is: SN 2023ixf

Recognition

Asteroid 1997 UN8 (/ List of minor planets: 14001–15000) was named in his honour. In 2009, he received the '' Edgar Wilson Award'' from the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

for the discovery of comet C/2009 E1. On 22 May 2023, supernova SN 2023ixf in the M101 galaxy, discovered by Itagaki three days previously, was featured on

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

's Astronomy Picture of the Day.

Early life

Amateur Astronomy

Recognition

References

See also