Anglo-Australian Telescope

Anglo-Australian Telescope
Observatory Australian Astronomical Observatory
Siding Spring Observatory Edit this on Wikidata
Location(s) New South Wales, Australia Edit this at Wikidata
Coordinates 31°16′31″S 149°04′01″E / 31.2754°S 149.067°E / -31.2754; 149.067Coordinates: 31°16′31″S 149°04′01″E / 31.2754°S 149.067°E / -31.2754; 149.067 Edit this at Wikidata
Organization Australian Astronomical Observatory Edit this on Wikidata
Altitude 1,100 m (3,600 ft) Edit this at Wikidata
Built –1974 Edit this on Wikidata (–1974 Edit this on Wikidata) Edit this at Wikidata
First light 27 April 1974 Edit this on Wikidata
Telescope style Cassegrain reflector
Optical telescope Edit this on Wikidata
Diameter 3.9 m (12 ft 10 in) Edit this at Wikidata
Collecting area 12 m2 (130 sq ft) Edit this at Wikidata
Focal length 12.7 m (41 ft 8 in) Edit this at Wikidata
Mounting Equatorial mount Edit this on Wikidata Edit this at Wikidata
Enclosure Spherical dome Edit this on Wikidata
Website www.aao.gov.au/about-us/anglo-australian-telescope Edit this at Wikidata
Location of Anglo-Australian Telescope

The Anglo-Australian Telescope (AAT) is a 3.9-metre equatorially mounted telescope operated by the Australian Astronomical Observatory and situated at the Siding Spring Observatory, Australia at an altitude of a little over 1,100 m. In 2009, the telescope was ranked as the fifth highest-impact of the world's optical telescopes. In 2001–2003, it was considered the most scientifically productive 4-metre-class optical telescope in the world based on scientific publications using data from the telescope.[1][2]

The telescope was commissioned in 1974 with a view to allowing high quality observations of the sky from the southern hemisphere. At the time, most major telescopes were located in the northern hemisphere, leaving the southern skies poorly observed.[3] It was the largest telescope in the Southern hemisphere from 1974-1976, then a close second to the Victor M. Blanco Telescope from 1976 until 1998, when the first ESO Very Large Telescope (VLT) was opened. The AAT was credited with stimulating a resurgence in British optical astronomy.[3] It was built by the United Kingdom in partnership with Australia but has been entirely funded by Australia since 2010.[4] Observing time is available to astronomers worldwide.

The AAT was one of the last large telescopes built with an equatorial mount. More recent large telescopes have instead adopted the more compact and mechanically stable altazimuth mount. The AAT was, however, one of the very first telescopes to be fully computer-controlled, and set new standards for pointing and tracking accuracy.

History

British astronomer Richard van der Riet Woolley pushed for a large optical telescope for the southern hemisphere in 1959.[3] In 1965, Macfarlane Burnet, president of the Australian Academy of Science, wrote to the federal education minister John Gorton inviting the federal government to support a joint British-Australian telescope project. Gorton was supportive, and nominated the Australian National University and CSIRO as Australia's representatives in the joint venture; he was unsuccessful in his attempts to induce NASA to join the project. Gorton brought the proposal before cabinet in April 1967, which endorsed the scheme and agreed to contribute half the capital and running costs. An agreement with the British was finalised a few weeks later and a Joint Policy Committee started work on construction planning in August 1967.[5] It took until September 1969 for plans to be finalised.[6] The agreement initially committed the specification to a telescope design based on the American Kitt Peak telescope until its deficiencies were known. Both the horseshoe mount and the gearing system needed improvements.[7] Although the revised gear system was considerably more expensive it was significantly more accurate, lending itself well to future applications.[7]

The mirror blank was made by Owens-Illinois in Toledo, Ohio. It was then transported to Newcastle, England where Sir Howard Grubb, Parsons and Co took two years to grind and polish the mirror's surface.[7] Mitsubishi Electric built the mount which was constructed by August 1973. First light occurred on 27 April 1974. The telescope was officially opened by Prince Charles on 16 October 1974.[7]

Structure and Telescope

The telescope is housed within a seven-story, circular, concrete building topped with a 36m diameter rotating steel dome. It was designed to withstand the high winds prevailing at that location. The slit is narrow. The dome is required to move with the telescope to avoid obstruction.[7] The top of the dome is 50m above ground level.

The telescope tube structure is supported inside a massive 12m diameter horseshoe, which rotates around the polar axis (parallel to Earth's axis) for tracking the sky. Total moving mass is 260 tonnes.[8]

The telescope has various foci for flexible instrumentation: originally there were three top-end rings which can be exchanged using the dome crane during the daytime. One was for f/3.3 prime-focus, with corrector lenses and a cage for a human observer taking photographs (rarely used after the 1980s); one has a large secondary mirror giving an f/8 Cassegrain focus; and a third top-end has smaller f/15 and f/36 secondary mirrors. A fourth top-end was built in the 1990s to give a 2-degree field of view at prime focus, with 400 optical fibres feeding the 2dF instrument and its later enhancements AAOmega and HERMES.

Instruments

3.9-metre equatorially mounted telescope

The AAT is equipped with a number of instruments, including :

HERMES will be commissioned in 2013. It is a new spectrograph to be used with the 2dF fibre positioner.[9] HERMES will be used for the 'Galactic Archaeology' (GA) Survey, which aims to reconstruct the history of our galaxy's formation from precise multi-element (~25) abundances of 1  million stars derived from HERMES spectra.

Comparisons

Largest optical astronomical telescopes in the late 1970s
# Name /
Observatory		 Image Aperture M1
Area		 Altitude First
Light
1. BTA-6
(Special Astrophysical Obs)		 238 inch
605 cm		 26 m2 2,070 m (6,790 ft) 1975
2. Hale Telescope
(Palomar Observatory)		 200 inch
508 cm		 20 m2 1,713 m (5,620 ft) 1949
3. Mayall Telescope
(Kitt Peak National Obs.)		 158 inch
401 cm		 10 m2 2,120 m (6,960 ft) 1973
4. Víctor M. Blanco Telescope
(CTIO Observatory)		 158 inch
401 cm		 10 m2 2,200 m (7,200 ft) 1976
5. Anglo-Australian Telescope
(Siding Spring Observatory)		 153 inch
389 cm		 12 m2 1,742 m (5,715 ft) 1974
6. ESO 3.6 m Telescope
(La Silla Observatory)		 140 inch
357 cm		 8.8 m2 2,400 m (7,900 ft) 1976
7. Shane Telescope
(Lick Observatory)		 120 inch
305 cm		 ~7 m2 1,283 m (4,209 ft) 1959

See also

References

  1. ↑ Fred Watson (6 January 2009). "Across the universe". The Sydney Morning Herald. Retrieved 8 November 2011.
  2. ↑ Tammy Plonter (11 September 2008). "Australian Telescope Leads the World in Astronomy Research". Universe Today.
  3. 1 2 3 Home, Roderick Weir (1990). Australian Science in the Making. Cambridge University Press. p. 360. ISBN 0521396409. Retrieved 6 December 2015.
  4. ↑ Nick Lomb (15 June 2010). "Australia's largest optical telescope to become part of the Australian Astronomical Observatory on 1 July 2010 and to celebrate its 36th birthday". Sydney Observatory.
  5. ↑ Ian Hancock (2002). John Gorton: He Did It His Way. Hodder. pp. 120–121.
  6. ↑ Gregory, Jane (2005). Fred Hoyle's Universe. Oxford University Press. p. 225. ISBN 0191578460. Retrieved 15 April 2013.
  7. 1 2 3 4 5 Haynes, Raymond (1996). Explorers of the Southern Sky: A History of Australian Astronomy. Cambridge University Press. pp. 382–394. ISBN 0521365759. Retrieved 15 April 2013.
  8. ↑ "The Anglo-Australian Telescope".
  9. ↑ "HERMES project AAT". Department of Industry, Innovation, Climate Change, Science, Research and Tertiary Education. Archived from the original on 9 April 2013. Retrieved 15 April 2013.
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