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The Anglo-Australian Telescope

Date created: 1977-08-01

Tags: AAT, Anglo-Australian Telescope, telescope, Siding Spring Observatory, SSO

The Anglo-Australian Telescope (AAT) was the last of a series of several 4m-class equatorial telescopes of similar design that were built in the mid 1970s, and it is one of three that were constructed in the southern hemisphere. The telescope is on Siding Spring Mountain in New South Wales, Australia, with its companion telescope, the 1.2m UK Schmidt Telescope. The telescopes, with offices and laboratories in the Sydney suburb of North Ryde, comprise the Australian Astronomical Observatory, successor organisation to the Anglo-Australian Observatory. Regularly scheduled observations began with the AAT in July, 1975, which operates every clear night of the year except for a few nights in the southern summer when the mirror is removed for re-aluminising.

Seen here pointing low in the east, the telescope is capable of looking anywhere in the southern sky more than 20 degrees above the horizon. It does so by swivelling on two axes. The motion which follows stars from east to west across the sky is defined by the yellow horseshoe bearing. This rotates resting on pads supported by pressurised oil. The second motion is around an axis between the arms of the horseshoe that permits the white structure holding the large mirror to tip north and south. At the end of the telescope is the tube-like prime focus 'cage' where light from the primary mirror is brought to a focus. It is from this focus that all the AAT colour photographs on these pages were made between 1978 and 2000, mostly using glass photographic plates. These plates were mostly intended for scientific purposes, but many of them were suitable for making 3-colour images using an additive process described here. Some care has been taken to ensure that the colour in the images derived from these plates is realistic, and reflects what the eye might be able to see it if it was much more sensitive to the colour of very faint light

Credit: David Malin

© Australian Astronomical Observatory