Mills Cross Telescope
Encyclopedia
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.
. 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 1963, the Fleurs site was transferred to the School of Electrical Engineering of The University of Sydney
. The observatory was effectively closed in 1991. The 18m 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.
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 Italy, Russia, and Ukraine.
Commonwealth Scientific and Industrial Research Organisation
The Commonwealth Scientific and Industrial Research Organisation is the national government body for scientific research in Australia...
in the area known now as Badgerys Creek
Badgerys Creek, New South Wales
-People:According to the 2006 census taken by the Australian Bureau of Statistics, Badgerys Creek had a population of 721, an improvement on the 1996 figure but still less than half the number in 1981. Well over half the houses were being rented , largely because of the federal government's...
, about 40km west of Sydney, New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
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.
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 PhysicsAustralian Journal of Physics
The Australian Journal of Physics was a peer-reviewed scientific journal published by the Commonwealth Scientific and Industrial Research Organisation in Australia. It was a journal for the publication of reviews covering all branches 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 1963, the Fleurs site was transferred to the School of Electrical Engineering of The University of Sydney
University of Sydney
The University of Sydney is a public university located in Sydney, New South Wales. The main campus spreads across the suburbs of Camperdown and Darlington on the southwestern outskirts of the Sydney CBD. Founded in 1850, it is the oldest university in Australia and Oceania...
. The observatory was effectively closed in 1991. The 18m dish antenna installed at Fleurs in 1959 was transferred to the Parkes Observatory
Parkes Observatory
The Parkes Observatory is a radio telescope observatory, 20 kilometres north of the town of Parkes, New South Wales, Australia. It was one of several radio antennas used to receive live, televised images of the Apollo 11 moon landing on 20 July 1969....
.
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.
Other cross telescopes
Fleurs was also the site of:- the Shain Cross Telescope, 1956 named after Alex Shain, solarSunThe Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
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 ChristiansenWilbur Norman ChristiansenWilbur Norman Christiansen was a pioneer Australian radio astronomer.Christiansen built the first grating array for scanning the sun at Potts Hill Reservoir. A later array at Badgerys Creek, New South Wales, the Chris Cross Telescope, was named for 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 ObservatoryParkes ObservatoryThe Parkes Observatory is a radio telescope observatory, 20 kilometres north of the town of Parkes, New South Wales, Australia. It was one of several radio antennas used to receive live, televised images of the Apollo 11 moon landing on 20 July 1969....
- 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 Italy, Russia, and Ukraine.
External links
- "The Flowering of Fleurs" - ATNF