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By Jupiter! A bad night on the ANU 16-inch

Tags: AAT

Night-time photography was always fraught with difficulties, especially in the days of film. The main problem was that film was slow, and especially slow when when light levels were low. For anything but star trial imagery, this obliged the night sky photographer to mount the camera on a tracking mount -- one that followed the stars by compensating the the Earth's rotation. When the images in this series were made, in the 1970 and 80s, such things were not common -- except on places like Siding Spring mountain, an observatory site run by the Australian National University, and also the home of the AAT.

The ANU had several telescopes there, not all of them used all the time. The smallest instrument, the 16-inch was often free. When I was not observing with the AAT, I could sometimes get access to it, and was allowed to fit it with a simple bracket on which I could fix a camera. The 16-inch usually tracked well, but the dome had to be moved by hand. however, it was a large aperture, so I could often leave it running for 30-40 minutes and do other things. Mostly this went well, and several of the pictures here were made using it, perhaps the most noteworthy being an image of Comet Halley. However, many things could go wrong.

The picture above is an 120-minute exposure of the central parts of the Milky Way, and the brightest 'star' Jupiter. As I left the dome with the telescope tracking and the shutter open, I neglected to turn off the very dim red safelight. I also advanced the dome shutter too far to the west, hence the red patch on the left. During the exposure, dew formed on the camera lens, providing an unwanted haze effect. And the camera lens was out of focus! Of course I did not know any of this until the film was developed some days later. Happily, I was observing on the AAT some nights later, and was able to attach the camera to it to capture Jupiter in the Milky Way.

Credit: David Malin

© Australian Astronomical Observatory