Australia's largest optical telescope to become part of the Australian Astronomical Observatory on 1 July 2010 and to celebrate its 36th birthday

Australia's largest optical telescope to become part of the Australian Astronomical Observatory on 1 July 2010 and to celebrate its 36th birthday

Published by Nick Lomb on June 15, 2010 No Comments

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The Anglo-Australian Telescope as it was in 1978. Attempted mosaic by Nick Lomb

Australia’s largest optical telescope, the 3.9-metre Anglo-Australian Telescope at Siding Spring in NSW, was jointly built and operated by the Australian and UK Governments. From 1 July 2010 the telescope and associated observatory will be Australian only and hence its name will change to the Australian Astronomical Observatory.

During the week before the transition and name change there will be a number of public talks and events at the town of Coonabarabran near the telescope. Among the talks there will be one by Dr David Malin who with his fantastic colour photographs of the southern sky did more than anyone to put the telescope on the international map. The events will also celebrate the 36th anniversary of the observatory.

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The Anglo-Australian Telescope dome, as seen from near Mt Stromlo’s 40-cm telescope in 1978. Picture Nick Lomb

Prince Charles inaugurated the telescope on 16 October 1974. Other dignatiries included the then Australian Prime Minister, EG Whitlam, and the famous British astronomer, Sir Fred Hoyle. Apart from the requisite speeches, the 500 invited guests heard music played by the Sydney Conservatorium String Quartet.

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The AAT is on the fringe of the Warrumbungle National Park. The spectacular scenery is made up of the weathered remains of an old shield volcano and its associated lava flows. Picture Nick Lomb

Regular observing began at the AAT in June 1975. Your blogger first visited there three years later as an assistant to Dr Alan Wright of the Anglo-Australian Observatory for a four night observing run. One night was completely cloudy while another started off with heavy rain. The forecast though was that the rain would end with thunderstorms and was to be followed by clear weather, Sure enough around midnight there was a major storm and then the sky cleared. The scheduled night assistant drove up from Coonabarabran, but could not cross the Castlereagh River because of flooding and hence there was no alternative to waking the head night assistant Tom Cragg who lived on Siding Spring Mountain to operate the telescope.

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A foggy morning on Siding Spring Mountain in 1978 seen from the catwalk of the AAT dome where it was still clear. Picture Nick Lomb

The telescope was under the control of an Interdata 70 computer. This computer and the associated computer programs were a key to the great success of the Anglo-Australian Telescope as it was the first telescope to be designed specifically to be controlled by a computer. In 2008/9 the Interdata 70 computer was “retired” from the telescope and it was acquired by the Powerhouse Museum with registration number 2009/41/1. The Statement of Significance includes

One of the main keys to the success of the telescope and its high international reputation was that it was the first large optical telescope built with computer controls. Initially there was serious opposition to this plan from senior astronomers as it was felt that that the computer system would turn out to be unreliable and a distraction. As a compromise traditional manual controls were also built into the telescope system together with the computer control. Fortunately, the manual system has only been used by engineers during tests and not during normal operation of the telescope.

The engineers building the control system managed to reach an accuracy in pointing the telescope of 1-2 arc seconds, which was unprecedented. This has had huge benefits in the efficiency of operating the telescope as no time is lost searching for and acquiring the target astronomical objects for observation with the appropriate instrument mounted on the telescope.

Happy anniversary Anglo-Australian Observatory and many successful years operating as the Australian Astronomical Observatory!

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