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The south celestial pole and star trails around the AAT

Tags: AAT

Several attempts were made to photograph this scene, which involved leaving a film camera outside all night with its shutter open. Many factors had to be right to obtain a 'perfect' image, whatever that may be. The night had to be moonless and cloud-free. The location had to produce an interesting composition, which limits the possibilities, and the night had to be dry, so no dew formed on the camera lens. The night also had to more or less windless, to avoid shaking the tripod. An unexpected hazard were kangaroos, who were curious about the new three-legged presence on their mountain and sometimes nudged it during the exposure. It was also wise not to tell anyone there was a camera pointing at the dome, because it can lead to mischief. Siding Spring Mountain is usually deserted at night, apart from astronomers, so camera thieves were not a problem. However, some drive cars around on parking lights, and here the camera was not far enough away from the road to avoid them, so unfortunately, unwanted trails were recorded during the 9 hour exposure.

Probably the most satisfactory of the many attempts, and the longest exposure (almost 11 hours) is here. The image shown here had an exposure of about eight hours. It was made in mid-February, in the southern summer, and the Southern Cross appears to be lying on its side, with the bright stars Alpha and Beta Centauri below it (left of the picture) in the early evening at that time of the year (February-March, 1979).

Credit: David Malin

© Australian Astronomical Observatory