Mills Cross Telescope
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Bernard Mills built the two-dimensional Mills Cross Telescope 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 40km west of Sydney, New South Wales, Australia.
Each arm of the cross was 1500 feet (450m) 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.
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[edit] Science
Between 1954 and 1957, Bernard Mills, Eric Hill and 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 C2 survey were a cause of scientific disquiet until serious questions about the C2 survey results were resolved several years later.
In the mid 1960s, Fleurs was transferred to the School of Electrical Engineering of the University of Sydney. It was effectively closed in 1991.
[edit] 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 W N 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 Molongolo Cross Telescope, near Canberra.
Other large cross-type radio telescopes were later built in Italy, Russia, and Ukraine.
[edit] References
[edit] External links
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- Street map from Street Directory, MSN Maps and Multimap.
- Satellite image from Google Maps, WikiMapia and Terraserver.
- "The Flowering of Fleurs" - ATNF
