astronomy

NGC 2805

NGC 2805 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 2805 rather than just read about it. In short: NGC 2805 is an intermediate spiral galaxy in the constellation of Ursa Major. Its velocity with respect to the cosmic microwave background is 1834 ± 7 km/s, which corresponds to a Hubble distance of 27.05 ± 1.90 Mpc (~88.2 million light-years).

Key takeaways

NGC 2805 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 2805 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 2805 from memory before moving on to harder problems.

Reference excerpt

NGC 2805 is an intermediate spiral galaxy in the constellation of Ursa Major. Its velocity with respect to the cosmic microwave background is 1834 ± 7 km/s, which corresponds to a Hubble distance of 27.05 ± 1.90 Mpc (~88.2 million light-years). However, 11 non redshift measurements give a distance of 12.76 ± 11.89 Mpc (41.6 million light-years). (Note: this sample of measurements is inconsistent: seven values between 3.03 Mpc and 5.13 Mpc are reported in publications from 1984 to 1985, then four values between 26.8 Mpc and 28.8 Mpc.) The galaxy was discovered by German-British astronomer William Herschel on 2 April 1791.

NGC 2805 Group NGC 2805 is the namesake of the NGC 2805 group (also known as LGG 173), which includes at least 4 other galaxies: NGC 2814, NGC 2820, NGC 2880, and IC 2458. This group, minus NGC 2880, are also collectively called Holmberg 124.

Supernova One supernova has been observed in NGC 2805: SN 2019hsw (Type II, mag. 15.4) was discovered by ASAS-SN on 18 June 2019.

See also List of NGC objects (2001–3000)

References

External links Media related to NGC 2805 at Wikimedia Commons NGC 2805 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 2805

Start with the simplest possible case. Write down what NGC 2805 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 2805 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 2805 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 2805

In research: NGC 2805 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 2805 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 2805 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1791, Discoveries by William Herschel, IRAS catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 2805 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 2805 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 2805 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 2805 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 2805 in simple terms?

Why does NGC 2805 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 2805?

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 2805.