Anglo-Australian Telescope

Anglo-Australian Telescope

Organisation	Australian Astronomical Observatory
Location(s)	Siding Spring Observatory, Australia
Coordinates
Altitude
Wavelength	optical, IR
Built	1974
First light	April 27, 1974 (1974-04-27)
Telescope style	prime/Cassegrain/coudé
Diameter	3.9 m (13 ft)
Collecting area	12 m2 (130 sq ft)
Focal length	12.7 m (42 ft)
Mounting	equatorial
Dome	spherical
Website	www.aao.gov.au/about/aat.html
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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.

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. 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 VLT was opened. The AAT was credited with stimulating a resurgence in British optical astronomy. It was constructed by Australia and the United Kingdom but has been entirely funded by Australia since 2010. 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

Richard van der Riet Woolley pushed for a large optical telescope for the southern hemisphere in 1959. A Joint Policy Committee started work on construction planning in August 1967. It took until September 1969 for plans to be finalised. The agreement initially committed the specification to a telescope design based on the Kitt Peak telescope until its deficiencies were known. Both the horseshoe mount and the gearing system needed improvements. Although the revised gear system was considerably more expensive it was significantly more accurate, lending itself well to unforeseen applications.

The mirror 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. 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.

Structure

The telescope is housed within a seven-story, circular, concrete building. 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. The dome structure is 118 feet (36 m) high.

Instruments

File:Anglo-Australian telescope at Siding Springs Observatory.jpg

3.9-metre equatorially mounted telescope

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

• The Two Degree Field facility (2dF), a robotic optical fibre positioner for obtaining spectroscopy of up to 400 objects over a 2° field of view simultaneously.
• The University College London Échelle Spectrograph (UCLES), a high-resolution optical spectrograph which has been used to discover many extrasolar planets.
• IRIS2, a wide-field infrared camera and spectrograph.

HERMES will be commissioned in 2013. It is a new spectrograph to be used with the 2dF fibre positioner. 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

The AAT was built just a little smaller and built later than the Mayall 4m, but the AAT views the southern sky.

Largest optical astronomical telescopes in the late 1970s

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

See also

• List of largest optical reflecting telescopes

External links

• Official website
• Online catalogue of building project papers (part of the Royal Greenwich Observatory Archives held at Cambridge University Library)