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| Alternative names | AAO |
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| Location | North Ryde,Sydney,New South Wales, AUS |
| Coordinates | 33°47′46″S151°08′42″E / 33.79621012°S 151.14511752°E /-33.79621012; 151.14511752 |
| Altitude | 1,164 m (3,819 ft) |
| Website | www |
| Telescopes | |
  Location of Australian Astronomical Observatory | |
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 Related media on Commons | |
TheAustralian Astronomical Observatory (AAO), formerly the Anglo-Australian Observatory, is an optical and near-infrared astronomyobservatory with its headquarters inNorth Ryde in suburbanSydney,Australia. Originally funded jointly by theUnited Kingdom andAustralian governments, it was managed wholly by Australia's Department of Industry, Innovation, Science, Research and Tertiary Education.[1][2] The AAO operated the 3.9-metreAnglo-Australian Telescope (AAT) and 1.2-metreUK Schmidt Telescope (UKST) atSiding Spring Observatory, located near the town ofCoonabarabran, Australia.
In addition to operating the two telescopes, AAO staff carried out astronomical research, and designed and built astronomical instrumentation for the AAT, UKST, and other telescopes including theEuropean Southern Observatory (ESO)'sVery Large Telescope in Chile, and the JapaneseSubaru Telescope onMauna Kea in Hawaii.
UK involvement in the AAO ceased in June 2010, with the change of name and management arrangements effective from 1 July 2010.[3]
In the years immediately afterWorld War II optical observational astronomy in the UK was toiling due to a lack of modern infrastructure. There were no large telescopes in theSouthern Hemisphere despite some of the most intriguing astronomical objects (e.g. theGalactic Center and theMagellanic Clouds) being best placed for study from these latitudes. In the 1950sRichard Woolley, Director ofMount Stromlo Observatory from 1939 to 1956 andAstronomer Royal from 1956 to 1971, suggested constructing a large telescope in Australia.
After a series of meetings between British and Australian scientists in the early 1960s to discuss the technical specifications and begin the search for a suitable site for the proposed telescope, a formal approach was made to the governments of both countries in July 1965. It was finally agreed in April 1967 that the building of a 150" telescope, theAnglo-Australian Telescope (AAT), should proceed. The telescope was to be located onSiding Spring Mountain in theWarrumbungles, which was owned by theAustralian National University (ANU) and the site of some of their existing infrastructure.
Later that year an interim body known as the Joint Policy Committee, and including prominent scientistsEdward Bowen (Aus),Olin Eggen (Aus),Richard Woolley (UK) and Jim Hosie (UK) was formed to oversee the early running of a project office which was located inCanberra. The project office finalised designs and specifications for the telescope, the mounting and the building and let contracts on a worldwide basis, exploiting the experience of those staff members who were involved in the development and construction of theParkes radio telescope.
The Anglo-Australian Telescope Agreement was signed on 25 September 1969 and came into effect on 22 February 1971. The Joint Policy Committee was replaced by the Anglo-Australian Telescope Board (AATB), an entity with full legal status under Australian law with responsibilities of overseeing the running of the telescope.
As construction of the AAT gathered pace, a heated debate ensued as to the details of the management structure which would control the telescope. Then Director of Mount Stromlo and Siding Spring Observatories,Olin Eggen and then Vice-Chancellor of the ANU,John Crawford, claimed that the bi-national agreement did not provide for the creation of a separate observatory. They argued that the telescope should ultimately be under the control of the Director of Mount Stromlo and Siding Spring Observatories and that additional staff for the new telescope should be provided by the ANU. However, fearing that they would be mere guests rather than equal partners in the AAT, British astronomers, with support from Australian state university astronomers, campaigned hard for a separate director and staff who were employed by and answerable only to the AATB. The matter was not settled until June 1973 when the Australian government endorsed the AATBs decision for an independent staff, marking the birth of the Anglo-Australian Observatory. The first director, Joe Wampler, took up his post in September 1974. To date[when?] there have been five directors.
In late-1967 the contract for the primary mirror blank was awarded toOwens-Illinois, USA and the 27.5 ton structure was cast from zero-expansionCervit glass in April 1969. The blank was shipped toNewcastle-upon-Tyne, England to be figured and polished byGrubb Parsons The final product has a diameter of 3.9m and a focal length of 12.7m.
Construction of the building and dome, undertaken by the Australian companiesLeighton Contractors[4] andEvans-Deakin Industries respectively, began in late-1970 and was completed by the end of 1972. The building was manufactured from concrete, stands 26m high and has seven floors housing offices, labs and a mirror aluminising chamber. The telescope stands on a concrete pier with a separate foundation to the main building, to reduce the risk of vibrations. The double skinned dome is manufactured from both steel and aluminium and weighs 570 tonnes.
The telescope is mountedequatorially, loosely following the design of the 4mKitt Peak National Observatory telescope. The mount was manufactured inMuroran,Japan byMitsubishi Electric. It was shipped to Australia in early 1973 before being assembled at Siding Spring Mountain in April of that year. The telescope drive system was also produced by Mitsubishi Electric and delivered at this time. It was one of the first to be controlled by computer, anInterdata Model 70, and provided new levels of pointing and tracking precision. Assembly of the AAT was completed by 1974 and commissioning of the telescope began in April of that year. In total it took eight years to build at a cost of A$16 million. It was inaugurated byHRH Prince Charles on 16 October 1974 and went into general use in June 1975.[5]
The AAO has made use ofoptical fibres in astronomy for over 25 years.[6] Instruments such as AAOmega, and its predecessor 2dF, use optical fibres to feed the light of stars and galaxies from the telescope into aspectrograph where it is dispersed into its component colours for detailed subsequent analysis. The broad field-of-view accessed by the 2dF and AAOmega instruments (4 times the width of the moon) and their 400 optical fibres, makes it feasible to spectroscopically survey large numbers of objects distributed across expansive areas of sky in a reasonable time frame.[7]
A number of major studies undertaken with the AAT have exploited these capabilities. The2dF Galaxy Redshift Survey (2dFGRS) used the 2dF instrument to obtain spectra andredshifts for ~250000 galaxies brighter than B~19.5 over ~7% of the southern sky in only ~270 nights. The 2dFGRS sample size was an order of magnitude greater than those of previous surveys, allowing a rigorous evaluation of cosmological parameters. For example, the survey has refined estimates of the mass density of the Universe, provided a determination of the fraction ofbaryonic matter in the Universe and set an upper limit on the total mass of neutrinos.[8] In addition 2dFGRS yielded an independent estimate of the Hubble constant, which was in excellent agreement with value determined by theHubble Space Telescope Key Project.[8]
The ongoingWiggleZ project is using the AAT and AAOmega to measure the redshifts of ~200000 distant luminous blue star forming galaxies distributed over an area of ~5000 times the area of the moon.[9] The primary goal of this study is to use an intrinsic feature in the distribution of galaxies as a "standard ruler" to relate distance to redshift and improve our knowledge of the nature of dark energy. This mysterious component of the Universe appears to be responsible for accelerating its rate of expansion.[10]
Another AAOmega based survey on the AAT,Galaxy and Mass Assembly (GAMA), is in the process of obtaining optical spectroscopy for ~250000 galaxies in the Local Universe.[when?] The AAOmega data will be used in conjunction with observations from satellite observatories such as theHerschel Space Observatory, and other telescopes around the world, to examine the predictions of the Cold Dark Matter standard cosmological model, like the relationship between the number density of dark matter halos and their masses and the relationship between the number density of galaxies and their masses as determined through studying their starlight.[11]
The AAT also hosts a program to search forextrasolar planets, theAnglo-Australian Planet Search (AAPS). The AAPS exploits the high stability of the University College London Echelle Spectrograph (UCLES) to obtain the few metres per second precision in measurements of the line-of-sight velocities of stars necessary to detect the reflexDoppler motion induced by the presence of a planet. The AAPS has found more than 20 extrasolar planets, with masses ranging from ~10% to > 10 times that of Jupiter.[12]
The 1.2-metreUK Schmidt Telescope was built to complement the AAT and officially began operations in August 1973. It was designed for survey astronomy, having an extremely large field-of-view which is more than 12 times the apparent diameter of the moon. The telescope was operated by the Schmidt Telescope Unit of theRoyal Observatory, Edinburgh until 1988, when it was agreed that control would be handed over to the AAO.
The Schmidt has undertaken work including blue and red photographic surveys of the southern sky and the6dF Galaxy Survey.[13] Its multi-object spectroscopic capability is currently being exploited to perform theRadial Velocity Experiment (RAVE) survey.[14]
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