Parkes Observatory

The 64-metre (210 ft) diameter dish with the 18-metre (59 ft) dish in the foreground (mounted on rails and used in interferometry)

The primary observing instrument is the 64-metre (210 ft) movable dish telescope, second largest in the Southern Hemisphere, and one of the first large movable dishes in the world (DSS-43 at Tidbinbilla was extended from 64-metre (210 ft) to 70-metre (230 ft) in 1987, surpassing Parkes).[7]

The inner part of the dish is solid aluminium and the outer area a fine aluminium mesh,[8] creating its distinctive two-tone appearance.

In the early 1970s the outer mesh panels were replaced by perforated aluminium panels. The inner smooth plated surface was upgraded in 1975 which provided focusing capability for centimetre- and millimetre-length microwaves.[9]

The inner aluminium plating was expanded out to a 55 metres (180 ft) diameter in 2003, improving signals by 1dB.[10]

The telescope has an altazimuth mount. It is guided by a small mock-telescope placed within the structure at the same rotational axes as the dish, but with an equatorial mount. The two are dynamically locked when tracking an astronomical object by a laser guiding system. This primary-secondary approach was designed by Barnes Wallis.

The radio telescope's focus cabin

The focus cabin is located at the focus of the parabolic dish, supported by three struts 27 metres (89 ft) above the dish. The cabin contains multiple radio and microwave detectors, which can be switched into the focus beam for different science observations.

These include:[11]

• 1,050-centimetre (34.4 ft) receiver (Replaced now by UWL)
• The Multibeam Receiver – a 13-horned receiver cooled at −200 °C (−328.0 °F; 73.1 K) for the 21-centimetre (8.3 in) Hydrogen line.[12][13]
• H-OH receiver (Replaced now by UWL)
• GALILEO receiver (Replaced now by UWL)
• AT multiband receivers, covering 2.2-2.5,4.5-5.1 and 8.1-8.7 GHz
• METH6, covering 5.9-6.8 GHz
• MARS (X band receiver), covering 8.1-8.5 GHz
• KU-BAND, covering 12–15 GHz
• 13MM (K band receiver), covering 16–26 GHz
• Ultra Wideband Low (UWL) receiver – installed in 2018 it can simultaneously receive signals from 700 MHz to 4 GHz.[14] It is cooled to −255 °C (−427.0 °F; 18.1 K) to minimise noise and will enable astronomers to work on more than one project at once.[6][15]

The 18-metre (59 ft) "Kennedy Dish" antenna was transferred from the Fleurs Observatory (where it was part of the Chris Cross Telescope) in 1963. Mounted on rails and powered by a tractor engine to allow the distance between the antenna and the main dish to be easily varied, it was used as an interferometer with the main dish. Phase instability due to an exposed cable meant that its pointing ability was diminished, but it was able to be used for identifying size and brightness distributions. In 1968 it successfully proved that Radio galaxy lobes were not expanding, and in the same era contributed to Hydrogen line and OH investigations. As a stand-alone antenna it was used in studying the Magellanic Stream.[16]

It was used as an uplink antenna in the Apollo program, as the larger Parkes telescope is receive-only.[17] It is preserved by the Australia Telescope National Facility.[18]

The observatory is a part of the Australia Telescope National Facility network of radio telescopes. The 64-metre (210 ft) dish is frequently operated together with the Australia Telescope Compact Array at Narrabri, the ASKAP array in Western Australia, and a single dish at Mopra, telescopes operated by the University of Tasmania as well as telescopes from New Zealand, South Africa and Asia to form a Very Long Baseline Interferometry (VLBI) array.

1960s

• Built in 1961 and was fully operational by 1963.
• A 1962 series of lunar occultations of the radio source 3C 273 observed by the Parkes Telescope were used to locate its exact position, allowing astronomers to find and study its visual component. Soon to be called "quasi-stellar radio sources" (quasar), Parkes observation was the first time this type of object to be associated with an optical counterpart.[19]
• 1964 to 1966, all-sky survey at 408 MHz of the southern sky is conducted and published (first version of the Parkes Catalogue of Radio Sources) finding over 2000 radio sources including many new quasars.[20]
• Second all-sky survey at 2,700 MHz begins in 1968 (completed in 1980).[20]

1990s

• June and November 1990, Parkes collaborates with the Massachusetts Institute of Technology and the National Radio Astronomy Observatory to conduct a 5GHZ (6 cm) all-sky survey (The Parkes-MIT-NRAO (PMN) Surveys). The Telescope is equipped with a NRAO multi-beam receiver operating at a frequency of 4850 MHz.[20][21]
• Between 1997 and 2002 it conducted the H I Parkes All Sky Survey (HIPASS) neutral hydrogen survey, the largest blind survey for galaxies in the hydrogen line (21-centimeter line or H I line) to date.

2000s

• More than half of currently known pulsars were discovered by the Parkes Observatory.
• Vital component of the Parkes Pulsar Timing Array[22] programme to detect gravity waves as part of the broader International Pulsar Timing Array (IPTA), which also includes the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) and the European Pulsar Timing Array (EPTA).

Fast radio bursts were discovered in 2007 when Duncan Lorimer of West Virginia University assigned his student David Narkevic to look through archival data recorded in 2001 by the Parkes radio dish.[23] Analysis of the survey data found a 30-jansky dispersed burst which occurred on 24 July 2001,[24] less than 5 milliseconds in duration, located 3° from the Small Magellanic Cloud.[25] At the time it was theorised FRBs might be signals from another galaxy, emissions from neutron stars or black holes.[26] More recent results confirm that magnetars, a kind of highly magnetised neutron star, may be one source of fast radio bursts.[27]

In 1998 Parkes telescope began detecting fast radio bursts and similar looking signals named perytons. Perytons were thought to be of terrestrial origin, such as interference from lightning strikes.[28][29][30][31] In 2015 it was determined that perytons were caused by staff members opening the door of the facility's microwave oven during its cycle.[32][33][34] When the microwave oven door was opened, 1.4 GHz microwaves from the magnetron shutdown phase were able to escape.[35] Subsequent tests revealed that a peryton can be generated at 1.4 GHz when a microwave oven door is opened prematurely and the telescope is at an appropriate relative angle.[36]

The telescope has been contracted to be used in a search for radio signals from extraterrestrial technologies for the heavily funded project Breakthrough Listen.[37][38] The principal role of the Parkes Telescope in the program will be to conduct a survey of the Milky Way galactic plane over 1.2 to 1.5 GHz and a targeted search of approximately 1000 nearby stars over the frequency range 0.7 to 4 GHz.

When Buzz Aldrin switched on the TV camera on the Lunar Module, three tracking antennas received the signals simultaneously. They were the 64-metre (210 ft) Goldstone antenna in California, the 26-metre (85 ft) antenna at Honeysuckle Creek near Canberra in Australia, and the 64-metre (210 ft) dish at Parkes.

Since they started the spacewalk early, the Moon was only just above the horizon and below the visibility of the main Parkes receiver. Although they were able to pick up a quality signal from the off axis receiver, the international broadcast alternated between signals from Goldstone and Honeysuckle Creek, the latter of which ultimately broadcast Neil Armstrong's first steps on the Moon worldwide.[42][39]

Celebrations on 19 July 2009 to mark the 40th anniversary of the Moon landing, and Parkes' role in it. "The Dish" behind is at full extension to the ground.

A little under nine minutes into the broadcast, the Moon rose far enough to be picked by the main antenna and the international broadcast switched to the Parkes signal. The quality of the TV pictures from Parkes was so superior that NASA stayed with Parkes as the source of the TV for the remainder of the 2.5-hour broadcast.[43][39]^{: 287–288}

In the lead up to the landing wind gusts greater than 100 km/h (62 mph) were hitting the Parkes telescope, and the telescope operated outside safety limits throughout the moonwalk.[39]^{: 300–301}

In 2012 the observatory received special signals from the Mars rover Opportunity (MER-B), to simulate the Curiosity rover UHF radio.[44] This helped prepare for the then upcoming Curiosity (MSL) landing in early August—it successfully touched down on 6 August 2012.[44]