science

Third Cambridge Catalogue of Radio Sources

Third Cambridge Catalogue of Radio Sources is a science 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 Third Cambridge Catalogue of Radio Sources rather than just read about it. In short: The Third Cambridge Catalogue of Radio Sources (3C) is an astronomical catalogue of celestial radio sources detected originally at 159 MHz, and subsequently at 178 MHz. History 3C The catalogue was published in 1959 by members of the Radio Astronomy Group of the University of Cambridge.

Key takeaways

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

Reference excerpt

The Third Cambridge Catalogue of Radio Sources (3C) is an astronomical catalogue of celestial radio sources detected originally at 159 MHz, and subsequently at 178 MHz.

History

3C The catalogue was published in 1959 by members of the Radio Astronomy Group of the University of Cambridge. Entries in the catalogue are identified by the prefix "3C" followed by the entry number, with a space—for example, 3C 273. The number denotes objects in order of increasing right ascension. The catalogue was produced using the Cambridge Interferometer on the west side of Cambridge. The interferometer had previously been used for the Second Cambridge Catalogue of Radio Sources (2C) survey, published in 1955.

3CR The catalogue was subsequently revised by Bennett in 1962 using observations at 178 MHz, and for many years '3CR' was considered as the definitive listing of the brighter radio sources in the Northern Hemisphere. The revision resulted in a number of sources being deleted from the catalogue (as being below the flux limit of 9 Jy or as now-resolved blends of adjacent sources) and others being added. To avoid renumbering the existing sources (which were listed in RA order) these new sources were added using a decimal extension. E.g. 3C 323.1 follows 3C 323 in Right Ascension and precedes 3C 324.

3CRR A further revision by R.A. Laing, Julia Riley and Malcolm Longair in 1983, called 3CRR or 3CR², included galaxies which were not detected in the original catalogue due to shortcomings of the original observations, but which otherwise meet the flux and declination limits. This revision includes all extragalactic radio sources in the Northern Hemisphere with 178-MHz flux density greater that 10.9 Janskys, declination greater than 10 degrees, and Galactic latitude greater than 10 degrees or less than -10 degrees. It excludes a number of well-known 3C/3CR objects, including all the supernova remnants from 3C, but also some well-known radio galaxies that lie outside the declination, flux density or galactic latitude constraints. Objects that had been discovered to consist of multiple components associated with different objects were given an alphabetical suffix (A, B...) to make it clear which component was part of the sample: e.g. the radio galaxy 3C 66B is part of the sample, but the BL Lac object 3C 66A is not.

References

External links The Revised 3C Catalogue of Radio Sources on the internet. The 3CRR catalogue on the internet.

Worked examples

Example 1 — a first encounter with Third Cambridge Catalogue of Radio Sources

Start with the simplest possible case. Write down what Third Cambridge Catalogue of Radio Sources claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Third Cambridge Catalogue of Radio Sources 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 Third Cambridge Catalogue of Radio Sources 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 Third Cambridge Catalogue of Radio Sources

In research: Third Cambridge Catalogue of Radio Sources appears in science 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 Third Cambridge Catalogue of Radio Sources 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: Third Cambridge Catalogue of Radio Sources is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3C objects, Cambridge surveys of radio sources, so understanding it makes those chapters shorter.
In everyday life: Look for Third Cambridge Catalogue of Radio Sources 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 Third Cambridge Catalogue of Radio Sources in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Third Cambridge Catalogue of Radio Sources 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 Third Cambridge Catalogue of Radio Sources out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Third Cambridge Catalogue of Radio Sources in simple terms?

The Third Cambridge Catalogue of Radio Sources (3C) is an astronomical catalogue of celestial radio sources detected originally at 159 MHz, and subsequently at 178 MHz. History 3C The catalogue was published in 1959 by members of the Radio Astronomy Group of the University of Cambridge.

Why does Third Cambridge Catalogue of Radio Sources matter?

Because it connects several science 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 Third Cambridge Catalogue of Radio Sources?

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 Third Cambridge Catalogue of Radio Sources.