is an amateur astronomer based in Yamagata, the capital city of Yamagata Prefecture in the TÃ Âhoku region of northern Honshu island, Japan. He is responsible for discovering many comets, and over 170 supernovae.
Itagaki had an early fascination with lenses, and used them to burn paper with concentrated sunlight.
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.
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 Zaà  Mountains (èµçÂÂé£峰, Zaà  Renpà Â) 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, in Okayama Prefecture, Chà «goku region of Honshu, around 700 kilometers to the southwest. In 2018, he built another remotely controlled telescope site on Shikoku 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.
One of his main discovery remains SN 2023ixf. As of late-2024, Itagaki's most recent discovery is: SN 2024abfl.
Asteroid 1997 UN8 (/) was named in his honour.
In 2009, he received the Edgar Wilson Award from the International Astronomical Union 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's Astronomy Picture of the Day.