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For over two decades the Anglo-Australian Observatory has provided world-class research facilities for both the Australian and British astronomical communities. The Observatory operates two optical telescopes at Siding Spring Observatory, the 3.9 metre Anglo-Australian Telescope and the 1.2 metre UK Schmidt Telescope, located outside the small town of Coonabarabran in northwest NSW, Australia, and adjacent to the magnificent Warrumbungle National Park . There is also a laboratory in the Sydney suburb of Epping. The Observatory was established at Siding Spring to take advantage of the extremely dark skies, and to provide the opportunity for astronomers to observe the southern sky where some of the most exciting objects are found, including the centre of our own Milky Way Galaxy and our neighbours the Magellanic Clouds.
The Observatory employs research scientists, computer programmers, electronics engineers, optical and mechanical engineers as well as technical and administrative staff. There are approximately sixty staff members; about half are located at Siding Spring Observatory, the other half at Epping in Sydney.
The AAO has been a world leader in astronomical research and instrumentation since it was opened in 1971. One of the reasons for this success is the vision and expertise of the Observatory's scientific and engineering staff, who have constantly upgraded both telescopes by incorporating the latest technological developments into instrument design. In fact, staff at the AAO are considered world leaders in many areas of astronomical instrumentation. AAO staff members also collaborate with scientists and engineers from other astronomical institutions in Australian and overseas, on a range of scientific and instrumentation projects. This close cooperation between reseachers and engineers is a powerful contibutor to the imaginative instrumentation for which the Observatory is known.
The most significant example of this capability is the new Two-Degree Facility (2dF) for the AAT. This new facility, which has been under development at the Observatory for the last five years, incorporates several innovative, high precision technologies and is by far the largest and most complex instrument of its type to be built anywhere in the world. It is a significant achievement for scientists and engineers at the AAO, who have pioneered many of the technologies, and is a credit to the scientific enterprise of the Australian and British astronomical communities. The 2dF will enable astronomers to carry out scientific research projects never before possible, providing a unique tool for astronomers to find answers to fundamental questions about the structure of the Universe.
Observing time on the AAO's telescopes is divided equally between the Australian and British astronomical communities. Most observers come from universities or research institutions in these two countries, but many projects involve collaboration with astronomers from other countries.
The Anglo-Australian Telescope Board
The AAO operates under an Agreement between Australia and the UK, and is funded equally by each government. The Anglo-Australian Telescope Board has overall responsibility for Observatory policy and for the direction of its development. At July 1996, the six members of the AAT Board are:
| Australia: Professor Lawrence Cram, University of Sydney (Chair) Professor Jeremy Mould, Mount Stromlo Observatory Professor Max Brennan, Australian Research Council United Kingdom: |
(Click here to see a picture of the AAT)
Commissioned in 1974, the Anglo-Australian Telescope was one of the last 4 metre equatorially mounted telescopes to be constructed. Its excellent optics, exceptional mechanical stability and precision computer control make it one of the finest telescopes in the world. Also important to the AAT's success has been its suite of state-of-the-art instrumentation, which is constantly being upgraded and improved. Until the 1970s, most of the world largest telescopes had been built in the northern hemisphere. To help redress the balance, the AAT was constructed in Australia so that astronomers could explore in detail some of the most exciting regions of the sky, including the centre of our own Milky Way Galaxy and its nearest neighbours the Magellanic Clouds. Some of the finest globular clusters and nearest radio galaxies can only be seen with difficulty from northern latitudes, if at all.
The AAT can be used in many configurations, each requiring a different instrument or detector to collect and analyse the light. Most astronomers use charge coupled devices (CCDs) to collect data. These highly sensitive solid state devices convert feeble light into digital signals which are then collected and stored on computers for further analysis, rather like an electronic photograph. However, traditional photography is also still used for special projects.
The most commonly used instruments on the AAT are its spectrographs, which split the light from distant objects into its constituent colours. Parts of the resulting spectrum can then be studied in detail to measure important properties such as the temperature, chemical composition, velocity or distance of an object, revealing vital facts about distant stars, galaxies and nebulae that photographs cannot show.
Other specialised instruments collect 'light' energy from the infrared (IR) region of the spectrum and are thus sensitive to the temperature of objects too cool to emit visible light. Using the most recent technical advances, the AAO has taken a lead in designing and building IR instruments, the latest of which, IRIS, provides both images and spectra of the sky. New IR instruments are currently under consideration. Infrared images are especially useful for studying the earliest stages of star formation, normally hidden at visible wavelengths by dust clouds.
Over the past decade the AAO has pioneered the use of optical fibres in astronomy and currently leads the world in this work. The latest of these instruments, the Two-Degree Field facility (or 2dF) uses flexible optical fibres, to collect the light from up to 400 faint stars or galaxies from a two degree field of view. This light is directed to a spectrograph, where the 400 individual spectra are detected by a CCD for analysis. Two degrees of sky is about four Moon diameters across, and is a four-fold increase in area of the AAT prime focus, which was already considered to be wide field for a 4m telescope. This instrument dramatically improves the efficiency of the telescope, which has traditionally observed one object at a time, allowing astronomers to carry out previously impractical observing projects.
A brief history of the AAT
The Anglo-Australian Telescope was established after representations had been made to the Australian and British Governments in the mid-1960s by the Australian Academy of Science and the Royal Society of London. It was decided in April 1967 to build a large optical telescope, similar in design to the 3.8 metre telescope of the Kitt Peak National Observatory in the United States. A site for the telescope was chosen on Siding Spring Mountain, near the New South Wales town of Coonabarabran, where the Australian National University had operated an observatory since 1965.
A Joint Policy Committee with representatives of each government served as an executive body from 1967 to 1971, when it was succeeded by the present Anglo-Australian Telescope Board. The Board operates under the authority of the Anglo-Australian Telescope Agreement which came into effect in 1971. Under this agreement, the costs of construction, operation and maintenance of the telescope were to be shared equally between the two Governments, while observing time would be similarly shared between astronomers in Australia and the UK.
A Project Office to supervise the construction of the telescope was set up in January 1968 by the Joint Policy Committee. Some two to three years were required for the preparation of detailed design specifications and the letting of major contracts, awarded on an international basis to companies in Japan, Switzerland and the United States, as well as from Australia and the UK. Figuring of the mirrors was carried out by the British firm, Sir Howard Grubb Parsons and Company Limited. The telescope mounting and the drive and control systems were manufactured by Mitsubishi Electric Corporation of Japan. The telescope building and dome, constructed by the Australian companies Leighton Constructions Limited and Evans-Deakin Industries Limited, were completed by the end of 1972 and the structural components of the telescope itself were assembled during 1973. The final cost of construction was $A15 932 250.
Following a detailed process of installation and commissioning of instrumentation, the AAT was inaugurated on 16 October 1974 by His Royal Highness, Prince Charles.
The primary mirror, which has a usable surface of diameter 3.89 metre, was aluminised late in 1974 and scientific work commenced early in 1975. Regularly scheduled observations began on 28 June 1975.
In October 1974 the Board established temporary quarters in the grounds of the CSIRO Division of Radiophysics at Epping, a suburb of Sydney, to provide technical and administrative support for the telescope. Subsequently, the Board decided to maintain this establishment, known since March 1976 as the Laboratory of the Anglo-Australian Observatory (AAO), as a complementary facility to the telescope on Siding Spring Mountain. The AAO Laboratory provides office, laboratory, library and computing facilities for scientific work, the development of instruments and software, administration and visiting astronomers.
(Click here to see a picture of the UKST)
The UK Schmidt Telescope (UKST) is a special purpose camera, a survey telescope with a very wide-angle field of view. It was designed to photograph 6.6 x 6.6 degree areas of the night sky on photographic plates 356 x 356 mm (14 x 14 inches) square. This 1.2m telescope was commissioned in 1973, and became part of the AAO in 1988. From 1973 to 1988, the UKST was operated by the Royal Observatory, Edinburgh.
The UKST's initial task was the first deep, blue-light photographic survey of the southern skies, which was completed in the 1980s. It has since undertaken many other survey projects in different colours and in the near infrared and more are in progress, notably the Second Epoch Sky Survey in collaboration with Space Telescope Science Institute. The excellent optics and wide field are now also exploited by FLAIR, a multi-object fibre-optic spectrographic facility, ideal for obtaining the spectra of up to 100 objects in a single field.
The characteristics of UKST and the AAT complement each other perfectly and many AAT projects depend on the wide field capabilities of the UKST. The telescopes of the Anglo-Australian Observatory have together discovered and confirmed more distant quasars, the most energetic but often the most distant objects in the Universe.
A brief history of the UKST
When the AAT project was already well underway in 1970, the British decided to build a 1.2 metre Schmidt telescope on Siding Spring Mountain. The Schmidt type of telescope is named after its inventor, Bernhard Schmidt, who discovered in the early 1930s that it was possible to build a telescope with a very wide field of view by a suitable combination of a spherical mirror and corrector-plate lens. The first large telescope of this type was the 48 inch Schmidt on Palomar Mountain, which carried out a complete photographic survey of the sky accessible from Palomar, from the north pole to -33° declination, during the early 1950s. This survey was reproduced as a set of photographs, and the resultant sky survey has been a fundamental database for northern hemisphere astronomers for forty years.
The then Science Research Council (SRC) established the UK Schmidt Telescope Project in 1971 as an independent project with the design, construction and operation under the direction of V C Reddish. The SRC set up a special Unit at the Royal Observatory, Edinburgh (ROE). Sir Howard Grubb Parsons & Company Limited of Newcastle-upon-Tyne, which also won the contract for the AAT mirror and tube assembly, began work on the Schmidt Telescope in June 1971. In May 1973 the telescope was delivered to Siding Spring, and the first plate was taken in the following month. The telescope was formally opened on 17 August 1973 by Professor Bengt Strömgren, President of the International Astronomical Union, and after completing initial commissioning it entered service on 3 September, just three days behind schedule. When Professor Reddish became Director of the ROE in 1975, the Schmidt Unit became part of that Observatory.
At about the same time the European Southern Observatory (ESO) built a 1.0 metre Schmidt telescope alongside its new 3.6 metre telescope on La Silla in Chile. As the primary objective of both Schmidt telescopes was to map the southern sky, the SERC and ESO agreed to share the survey work, with the UK Schmidt taking plates in blue light and ESO the corresponding set of red photographs. The ESO/SERC Southern Sky Survey covers the sky from -17° to the south pole with a mosaic of 606 photographic plates in each colour. The survey plates were copied onto glass and film at the ESO Sky Atlas Laboratory, and the resulting Atlas has been distributed to some 170 institutions around the world. This atlas is now also widely available in digital form. The UK Schmidt also carried out a photographic near infrared survey of the Milky Way which has been widely distributed as an atlas made in the ROE Photolabs, and a new atlas of the equatorial strip of sky is now being produced.
In 1988 the SERC concluded negotiations with the Board for the Schmidt Telescope to become part of the Anglo-Australian Observatory, operated like the AAT under the AAO Director, and funded jointly by the two Governments. The Plate Library at ROE remains the ultimate destination of all Schmidt Telescope plates, and has a unique archive of over 10,000 sky photographs. Other facilities in the UK, the Photolabs at ROE and the high-speed measuring machines, remain closely linked with the Schmidt Telescope operations in Australia.
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Sandra Harrison, sjh@aaoepp.aao.gov.au
July 1996
