astronomy

PKS 2142−758

PKS 2142−758 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 PKS 2142−758 rather than just read about it. In short: PKS 2142−758 is a blazar located in the southern constellation of Octans. Its redshift is (z) 1.144 and it was first discovered as a quasar candidate during the Parkes 2700 MHz survey by astronomers in 1979.

Key takeaways

PKS 2142−758 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PKS 2142−758 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PKS 2142−758 from memory before moving on to harder problems.

Reference excerpt

PKS 2142−758 is a blazar located in the southern constellation of Octans. Its redshift is (z) 1.144 and it was first discovered as a quasar candidate during the Parkes 2700 MHz survey by astronomers in 1979. The radio spectrum of PKS 2141−758 is flat, making it a flat-spectrum radio quasar. It displays redder-stable-when brighter (RSWB) spectral variations.

Description PKS 2142−758 is highly active on the electromagnetic spectrum. It was found to produce several significant gamma-ray flares detected through MeV and GeV energy ranges, which started on April 4, 2010. During observations by the AGILE satellite at that time, the daily flux of the source reached 2.6 ± 0.9 10−6 photons cm−2 s−1. Another flare was detected on May 20, 2014, by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope, where the flux level reached 1.2 ± 0.3 × 10−6 photons cm−2 s−1. Between December 2011 and January 2012, PKS 2142−758 was in a quiescent state with a 100 MeV to 300 GeV luminosity of 4.4 × 1048 erg s−1. This makes it one of the most luminous sources observed. A new flare was observed on November 7, 2014. When shown on a B-band optical curve, the flare was found to be the brightest known with a magnitude of 16.585. It lasted for 1,610 days, during which its light variation magnitude reached a peak of 1.329. A study published in May 2025 also showed most of the optical outbursts in PKS 2142−758 occurred at a large distance from the torus area. The source of PKS 2142−758 is found mainly dominated by a radio core structure according to Very Long Baseline Interferometry radio imaging at first-epoch. There is a faint jet extending toward the east. A central supermassive black hole mass has been found for PKS 2142−758. Based on data observations, it is estimated at 1 billion M☉ with total luminosity of 6.5 × 1045 erg s−1.It has an accretion disk with its inner radius being 1.5 × 1014 cm or 6 Rg and the outer radius of the disk is approximately 1 × 104 Rg. The temperature of the disk is in the range of 1.3-1.4 × 104 k (± 0.04).

References

External links PKS 2142−758 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images PKS 2142−758 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with PKS 2142−758

Start with the simplest possible case. Write down what PKS 2142−758 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 PKS 2142−758 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 PKS 2142−758 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 PKS 2142−758

In research: PKS 2142−758 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 PKS 2142−758 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: PKS 2142−758 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Active galaxies, Astronomical objects discovered in 1979, Blazars, so understanding it makes those chapters shorter.
In everyday life: Look for PKS 2142−758 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 PKS 2142−758 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PKS 2142−758 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 PKS 2142−758 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PKS 2142−758 in simple terms?

Why does PKS 2142−758 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 PKS 2142−758?

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 PKS 2142−758.