Anglo-Australian Telescope

Anglo-Australian Telescope

Part of	Australian Astronomical Observatory Siding Spring Observatory
Location(s)	New South Wales, AUS
Coordinates	31°16′31″S 149°04′01″E / 31.2754°S 149.067°E / -31.2754; 149.067
Organization	Australian Astronomical Observatory
Altitude	1,100 m (3,600 ft)
Built	–1974 (–1974)
First light	27 April 1974
Telescope style	Cassegrain reflector optical telescope
Diameter	3.9 m (12 ft 10 in)
Collecting area	12 m2 (130 sq ft)
Focal length	12.7 m (41 ft 8 in)
Enclosure	spherical dome
Website	www.aao.gov.au/about-us/anglo-australian-telescope
Location of Anglo-Australian Telescope
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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 having 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 to 1976, then a close second to the Víctor 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 first telescopes to be fully computer-controlled, and set new standards for pointing and tracking accuracy.