Minor planet 1036 Ganymed


 Minor planet 1036 Ganymed

Canon EOS 5D MkII ISO6400 31x30s 254mm Newtonian f/9.6 (f=2400mm, Barlow)
HEQ5 mount, driven but not guided 2011 Sep 29 21:43:41-22:13:49 UT
From Rookhope 54.8N 2.1W 330m asl. Rural, almost no light pollution (3 Bortles)

Frames were exposed at 1 minute intervals. Field of view of this cropped image is 0.41 x 0.36 degrees. Images were stacked and then scaled linearly from 32 to 8 bits per channel but not processed in any other way.

Ganymed was of comparable brightness to the 3 brightest stars in the field but of course they have been added up 31 times while Ganymed has been spread along the trail. I plan to do magnitude measurements on the individual frames.

Ganymed is moving faster across the sky than most asteroids because it is only 0.38 au* from us at the moment. Although this is a crop of the full frame, at 2400mm and 1 minute intervals the movement from one frame to the next was obvious on camera playback.

* au = Astronomical Unit, the mean radius of the Earth's orbit around the Sun.

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