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](_blank)
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.
References
See also
*
:it:Koichi Itagaki Short biography and lists of discoveries, on Italian Wikipedia
*
Kaoru Ikeya
*
List of minor planet discoverers
{{DEFAULTSORT:Itagaki, Kōichi
Discoverers of comets
Discoveries by Koichi Itagaki
20th-century Japanese astronomers
21st-century Japanese astronomers
Living people
People from Yamagata (city)
Year of birth missing (living people)
Scientists from Yamagata Prefecture
it:14551 Itagaki