The Molonglo Observatory Synthesis Telescope (MOST) is a

radio telescope A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency ...

operating at 843 MHz. It is operated by the School of Physics of the

University of Sydney The University of Sydney (USYD), also known as Sydney University, or informally Sydney Uni, is a public research university located in Sydney, Australia. Founded in 1850, it is the oldest university in Australia and is one of the country's si ...

. The telescope is located in

Hoskinstown Hoskinstown is a locality in Queanbeyan-Palerang Regional Council, New South Wales, Australia. The locality, and what remains of the cluster of settlement of the same name, is 38 km southeast of Canberra the Capital city of Australia, and 299 k ...

, near the

Molonglo River The Molonglo River, a perennial river that is part of the Murrumbidgee catchment within the Murray–Darling basin, is located in the Monaro and Capital Country regions of New South Wales and the Australian Capital Territory, in Australia. ...

and

Canberra Canberra ( ) is the capital city of Australia. Founded following the federation of the colonies of Australia as the seat of government for the new nation, it is Australia's largest inland city and the eighth-largest city overall. The ci ...

, and was constructed by modification of the east–west arm of the former Molonglo Cross Telescope, a larger version of the Mills Cross Telescope.

Design

The MOST consists of two cylindrical paraboloids, 778m x 12m, separated by 15m and aligned east–west. A line feed system of 7744 circular dipoles collects the signal and feeds 176 preamplifiers and 88 IF amplifiers. The telescope is steered by mechanical rotation of the cylindrical paraboloids about their long axis, and by phasing the feed elements along the arms. The feed elements were decommissioned in 2018 so that the telescope began to operate in transit mode only. Prior to this, the `alt-alt' system could follow a field for ± 6 hours (necessary for a complete

aperture synthesis Aperture synthesis or synthesis imaging is a type of interferometry that mixes signals from a collection of telescopes to produce images having the same angular resolution as an instrument the size of the entire collection. At each separation and ...

with an east–west array) for fields south of declination -30 degrees. For fields near this limit the signal-to-noise ratio is lower for the first and last hour or so due to the lower gain of the system at large '

meridian arc In geodesy and navigation, a meridian arc is the curve between two points on the Earth's surface having the same longitude. The term may refer either to a segment of the meridian, or to its length. The purpose of measuring meridian arcs is to ...

distance' angles. The Molonglo Cross Telescope was a 408 MHz

built by Bernard Y. Mills and collaborators and operated by the

. It telescope consisted of a north–south arm and an east–west arm in a cross shape. Each arm was approximately one mile in length. The east–west arm was split into 88 individual elements to form the current Molonglo Observatory Synthesis Telescope.

Grote Reber

The design of the original system owes much to pioneering radio astronomy by

Grote Reber Grote Reber (December 22, 1911 – December 20, 2002) was an American pioneer of radio astronomy, which combined his interests in amateur radio and amateur astronomy. He was instrumental in investigating and extending Karl Jansky's pioneering wo ...

in the US and Australia, that informed Mills' work. A memorial to Reber, including some of his ashes, is sited at the telescope.

MOST work

Much pioneering radio astronomy was done with this telescope. The Molonglo Cross Telescope was used for a survey of the Southern sky with a resolution of 2.8 arc-min. The telescope's main research project was the

Sydney University Molonglo Sky Survey The Molonglo Observatory Synthesis Telescope (MOST) is a radio telescope operating at 843 MHz. It is operated by the School of Physics of the University of Sydney. The telescope is located in Hoskinstown, near the Molonglo River and Canberra, ...

(SUMSS), a sensitive radio imaging survey of the southern sky at 843 MHz with similar resolution and sensitivity to the northern

NRAO VLA Sky Survey The NRAO VLA Sky Survey (NVSS) was an astronomical survey of the Northern Hemisphere carried out by the Very Large Array (VLA) of the National Radio Astronomy Observatory (NRAO), resulting in an astronomical catalogue. It was led by James J. Con ...

(NVSS). SUMSS is now complete, and digital images and a source catalogue are available online. After a five-year break in which analog equipment was upgraded the observatory is now used to detect

fast radio burst In radio astronomy, a fast radio burst (FRB) is a transient radio pulse of length ranging from a fraction of a millisecond to 3 seconds, caused by some high-energy astrophysical process not yet understood. Astronomers estimate the average FRB rel ...

s and do research on

pulsar A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...

s. The equipment for fast radio burst detection is called UTMOST.

Square Kilometre Array development

MOST is being used to develop technology for the Australian site of the Square Kilometre Array telescope. Since 2003 work has proceeded on the SKA Molonglo Prototype (SKAMP) which has included fitting new wide-band feeds, low-noise amplifiers, digital filterbanks and correlator, in order to demonstrate 300- 1420 MHz continuous frequency coverage and multibeam mode operation. The new correlator is a 96 input continuum correlator using

Field Programmable Gate Array A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term '' field-programmable''. The FPGA configuration is generally specified using a hardware ...

(FPGA) chips. This effort is a collaboration between the

Australia Telescope National Facility The Commonwealth Scientific and Industrial Research Organisation (CSIRO)'s radio astronomy observatories are collectively known as the Australia Telescope National Facility (ATNF), with the facility supporting Australia's research in radio astron ...

(ATNF), the Australian

Commonwealth Scientific and Industrial Research Organisation The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency responsible for scientific research. CSIRO works with leading organisations around the world. From its headquarters in Canberra, CSIRO ...

(CSIRO)

Information and Communications Technology Information and communications technology (ICT) is an extensional term for information technology (IT) that stresses the role of unified communications and the integration of telecommunications ( telephone lines and wireless signals) and computer ...

Centre, and the University of Sydney.

UTMOST

Since 2015, the telescope has been operated in a collaboration between the University of Sydney and Swinburne University of Technology. The goal is to probe the radio transient sky in real time, monitoring pulsars and magnetars, and searching for Fast Radio Bursts. The telescope sensitivity was improved by a refit of receiver technologies on one of its arms (in the east–west direction), and presently (late 2020) the north–south arm is being fitted out with significantly improved receivers as well. This will allow Fast Radio Bursts and similar radio transients to be located on the sky with a few arcseconds of precision, sufficient to identify the host galaxies from which the originate.

Notes

References

External links

* {{Portal bar, New South Wales, Australia, Astronomy, Stars, Spaceflight, Outer space, Solar System, Education, Science Astronomical observatories in New South Wales Radio telescopes Interferometric telescopes University of Sydney