astronomy

NGC 3689

NGC 3689 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 3689 rather than just read about it. In short: NGC 3689 is an intermediate spiral galaxy in the constellation of Leo. Its velocity with respect to the cosmic microwave background is 3049 ± 22 km/s, which corresponds to a Hubble distance of 44.97 ± 3.16 Mpc (~147 million light-years).

Key takeaways

NGC 3689 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 3689 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 3689 from memory before moving on to harder problems.

Reference excerpt

NGC 3689 is an intermediate spiral galaxy in the constellation of Leo. Its velocity with respect to the cosmic microwave background is 3049 ± 22 km/s, which corresponds to a Hubble distance of 44.97 ± 3.16 Mpc (~147 million light-years). However, 16 non-redshift measurements give a closer distance of 39.350 ± 2.088 Mpc (~128 million light-years). The galaxy was discovered by German-British astronomer William Herschel on 6 April 1785. NGC 3689 is a radio galaxy, i.e. it has giant regions of radio emission extending well beyond its visible structure. The SAGA Astronomical Survey for the search for satellite galaxies orbiting another galaxy confirmed the presence of two satellite galaxies for NGC 3689.

Supernovae Two supernovae have been observed in NGC 3689:

AT 2024mxe (type Gap, mag. 17.7) was a calcium-rich supernova discovered by GOTO on 26 June 2024. SN 2026gwx (Type Ib, mag. 20.8896) was discovered by the Zwicky Transient Facility on 20 March 2026. It had been initially classified as Type Ia, but later analysis concluded it was Type Ib.

See also List of NGC objects (3001–4000)

References

External links Media related to NGC 3689 at Wikimedia Commons NGC 3689 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Illustrations

Worked examples

Example 1 — a first encounter with NGC 3689

Start with the simplest possible case. Write down what NGC 3689 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 3689 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 3689 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 3689

In research: NGC 3689 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 3689 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 3689 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1785, Discoveries by William Herschel, Intermediate spiral galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 3689 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study NGC 3689 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 3689 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 3689 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 3689 in simple terms?

Why does NGC 3689 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 3689?

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 3689.