astronomy

NGC 819

NGC 819 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 NGC 819 rather than just read about it. In short: NGC 819 is a spiral galaxy approximately 302 million light-years away from Earth in the constellation of Triangulum. It forms a visual pair with the galaxy NGC 816 5.7' WNW.

Key takeaways

NGC 819 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NGC 819 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 819 from memory before moving on to harder problems.

Reference excerpt

NGC 819 is a spiral galaxy approximately 302 million light-years away from Earth in the constellation of Triangulum. It forms a visual pair with the galaxy NGC 816 5.7' WNW.

Discovery NGC 819 was discovered by German astronomer Heinrich Louis d'Arrest on September 20, 1865 with the 11-inch refractor at Copenhagen. Édouard Stephan independently found the galaxy again on September 15, 1871 with the 31" reflector at Marseille Observatory.

Supernovae Four supernovae have been observed in NGC 819:

SN 2007hb (Type Ib/c, mag. 19.5) was discovered by Nearby Supernova Factory on August 24, 2007. It was located at RA 02h 08m 34.0s, DEC +29° 14′ 14″, J2000.0. SN 2016hkn (Type II, mag. 17.2) was discovered by Paolo Campaner on October 22, 2016. It was located at RA 02h 08m 34.23s, DEC +29° 14′ 11.1″. SN 2020mbe (Type Ic, mag. 18.6) was discovered by Gaia Photometric Science Alerts on January 10, 2020. SN 2026fau (Type II, mag. 18.5942) was discovered by the Zwicky Transient Facility on March 7, 2026.

Illustrations

Worked examples

Example 1 — a first encounter with NGC 819

Start with the simplest possible case. Write down what NGC 819 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 NGC 819 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 NGC 819 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 NGC 819

In research: NGC 819 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 NGC 819 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: NGC 819 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1865, Discoveries by Heinrich Louis d'Arrest, IRAS catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 819 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 NGC 819 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 819 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 NGC 819 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 819 in simple terms?

NGC 819 is a spiral galaxy approximately 302 million light-years away from Earth in the constellation of Triangulum. It forms a visual pair with the galaxy NGC 816 5.7' WNW.

Why does NGC 819 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 NGC 819?

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 NGC 819.