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Mills Cross Telescope

Mills Cross Telescope 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 Mills Cross Telescope rather than just read about it. In short: The Mills Cross Telescope was a two-dimensional radio telescope built by Bernard Mills in 1954 at the Fleurs field station of the Australian Commonwealth Scientific and Industrial Research Organisation in the area known now as Badgerys Creek, about 40 km west of Sydney, New South Wales, Australia. Each arm of the cross was 1500 feet (450 m) long, running N–S and E–W, and produced a fan beam in the sky.

Mills Cross Telescope — main illustration
Mills Cross Telescope — illustration

Key takeaways

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

Reference excerpt

The Mills Cross Telescope was a two-dimensional radio telescope built by Bernard Mills in 1954 at the Fleurs field station of the Australian Commonwealth Scientific and Industrial Research Organisation in the area known now as Badgerys Creek, about 40 km west of Sydney, New South Wales, Australia. Each arm of the cross was 1500 feet (450 m) long, running N–S and E–W, and produced a fan beam in the sky. Mills said it "consists of two rows of 250 half-wave dipole elements backed by a plane wire mesh reflector; the individual dipoles are aligned in an E-W direction." The cross operated at a frequency of 85.5 MHz (3.5m wavelength), giving a 49 arcminute beam. When the voltages of the two arms were multiplied a pencil beam was formed, but with rather high sidelobes. The beam could be steered in the sky by adjusting the phasing of the elements in each arm.

Science Between 1954 and 1957, Bernard Mills, Eric R. Hill and O. Bruce Slee, using the Mills Cross, carried out a detailed survey of the sky and recorded over 2,000 sources of discrete radio emission, publishing results in a series of research papers in the Australian Journal of Physics. The differences between these sources and the Cambridge 2C survey were a cause of scientific disquiet until serious questions about the 2C survey results were resolved several years later. In 1963, the Fleurs site was transferred to the School of Electrical Engineering at the University of Sydney. The observatory was effectively closed in 1991. The 18 m dish antenna installed at Fleurs in 1959 was transferred to the Parkes Observatory. Two of the old 13.7m dish antennas were relocated from the University of Sydney site to the CSIRO at Marsfield in 2005, as part of a precursor study into the Square Kilometer Array (SKA) development. Until 1961, astronomers Mills, Slee, and Hill published their Catalogue of Radio Sources (later known as the MSH Catalogue after their surnames), in which some 2,300 of discrete radio emissions were introduced.

Other cross telescopes Fleurs was also the site of:

the Shain Cross Telescope, 1956 named after Alex Shain, solar observatory 19.7 MHz, beam width of 1.4 degrees, N–S and E-W arms of 1105 m and 1036 m respectively the Chris Cross Telescope, 1957 named after Dr. Wilbur Norman Christiansen, solar observatory N–S and E-W arms each 378m containing 32 parabolic dishes 5.8m in diameter in 1959, an 18m parabola was installed at the eastern end of the Chris Cross, moved in 1963 to the Parkes Observatory then, six 13.7m stand-alone antennas were sited at and beyond the ends of the N–S and E–W solar arrays, which comprised the Fleurs Synthesis Telescope with a resolving power of 20 arc seconds, used in the 1970s and until its closure in 1988 studying individual radio sources but particularly large radio galaxies, supernova remnants and emission nebulae. Following the success of this design, Mills built another large cross antenna, the Molonglo Cross Telescope, near Canberra. Other large cross-type radio telescopes were later built in the United States, Italy, Russia, and Ukraine.

See also Lists of telescopes

References

Sources "A new southern hemisphere synthesis radio telescope", Christiansen, W.N. Proceedings of the IEEE, Volume 61, Issue 9, September 1973 Page(s): 1266 – 1270 "A Catalogue of Radio Sources between Declinations +10° and −20°", Mills, B. Y.; Slee, O. B.; Hill, E. R. Australian Journal of Physics, Volume 11, Issue 3, September 1958, Page(s): 360 – 387, ADS:1958AuJPh..11..360M "A Catalogue of Radio Sources between Declinations −20° and −50°", Mills, B. Y.; Slee, O. B.; Hill, E. R. Australian Journal of Physics, Volume 13, December 1960, Page(s): 676, ADS:1960AuJPh..13..676M "A Catalogue of Radio Sources between Declinations −50° and −80°", Mills, B. Y.; Slee, O. B.; Hill, E. R. Australian Journal of Physics, Volume 14, December 1961, Page(s): 497, ADS:1961AuJPh..14..497M

External links Media related to Mills Cross Telescope at Wikimedia Commons

"The Flowering of Fleurs" – ATNF

Illustrations

Mills Cross Telescope: The Mills Cross at Fleurs, looking S along part of the N-S arm, with the receiver house conspicuous at the centre of the array. A fence around the array kept the animals out.
The Mills Cross at Fleurs, looking S along part of the N-S arm, with the receiver house conspicuous at the centre of the array. A fence around the array kept the animals out.

Worked examples

Example 1 — a first encounter with Mills Cross Telescope

Start with the simplest possible case. Write down what Mills Cross Telescope 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 Mills Cross Telescope 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 Mills Cross Telescope 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 Mills Cross Telescope

In research
Mills Cross Telescope 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 Mills Cross Telescope 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
Mills Cross Telescope is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1954 establishments in Australia, 1991 disestablishments in Australia, Astronomical observatories in New South Wales, so understanding it makes those chapters shorter.
In everyday life
Look for Mills Cross Telescope 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 Mills Cross Telescope in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Mills Cross Telescope means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Mills Cross Telescope out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mills Cross Telescope in simple terms?

The Mills Cross Telescope was a two-dimensional radio telescope built by Bernard Mills in 1954 at the Fleurs field station of the Australian Commonwealth Scientific and Industrial Research Organisation in the area known now as Badgerys Creek, about 40 km west of Sydney, New South Wales, Australia…

Why does Mills Cross Telescope 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 Mills Cross Telescope?

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 Mills Cross Telescope.

Tags

  • 1954 establishments in Australia
  • 1991 disestablishments in Australia
  • Astronomical observatories in New South Wales
  • Australian inventions
  • Interferometric telescopes
  • Radio telescopes
  • University of Sydney

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