astronomy

Kōichi Itagaki

Kōichi Itagaki is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Kōichi Itagaki rather than just read about it. In short: Kōichi Itagaki (Japanese: 板垣公一, Hepburn: Itagaki Kōichi; born 12 November 1947) is an amateur astronomer based in Yamagata, the capital city of Yamagata Prefecture in the Tōhoku region of northern Honshu island, Japan. He is responsible for discovering many comets, and over 170 supernovae.

Key takeaways

Kōichi Itagaki belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kōichi Itagaki to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kōichi Itagaki from memory before moving on to harder problems.

Reference excerpt

Kōichi Itagaki (Japanese: 板垣公一, Hepburn: Itagaki Kōichi; born 12 November 1947) is an amateur astronomer based in Yamagata, the capital city of Yamagata Prefecture in the Tōhoku region of northern Honshu island, Japan. He is responsible for discovering many comets, and over 170 supernovae.

Early life 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 15 centimetres (5.9 in) 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 60 centimetres (24 in), 50 centimetres (20 in), and 11 centimetres (4.3 in) telescopes and a hut for the associated equipment. In 2015, he built an automated telescope site near Okayama, in Okayama Prefecture, Chūgoku 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.

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 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.

References

See also it:Koichi Itagaki Short biography and lists of discoveries, on Italian Wikipedia Kaoru Ikeya List of minor planet discoverers

Worked examples

Example 1 — a first encounter with Kōichi Itagaki

Start with the simplest possible case. Write down what Kōichi Itagaki claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Kōichi Itagaki before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Kōichi Itagaki ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Kōichi Itagaki

In research: Kōichi Itagaki appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Kōichi Itagaki in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Kōichi Itagaki is common in secondary-school and first-year university syllabi. It links to neighbouring topics 20th-century Japanese astronomers, 21st-century Japanese astronomers, Discoverers of comets, so understanding it makes those chapters shorter.
In everyday life: Look for Kōichi Itagaki outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Kōichi Itagaki in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kōichi Itagaki means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Kōichi Itagaki out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kōichi Itagaki in simple terms?

Why does Kōichi Itagaki matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Kōichi Itagaki?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Kōichi Itagaki.