Commissioned in 1974 (read a brief history), the Anglo-Australian Telescope (ATT) 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.
 

Photo: Dome of the Anglo-Australian Telescope.

AAT is a leg of Around the World in 80 Telescopes tour: Click to play; click  (lower right) to view video full screen Next stop: GEO600 Gravitational (previous stop: MOA)

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.

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