The image above is a composite of twenty five 100 second frames captured of the 103PHartley comet on October 6, 2010, from about 1 minute after midnight to 45 minutes after. At that time, the comet was mid-way beteen Cassiopeia and Perseus. The image is a link to a video (.mov format, about 28 MB) showing 24 of the 25 frames in sequence (the first being too dim for some reason). This comet was a little irritating - it moved too quickly for long exposures, and too slowly to make a very interesting video. A slight sideways movement of the comet nucleus between frames is a result of the finite resolution of the individual frames, which could not be perfectly registered: it moved in a straight line. The image above shows the track it formed over the time period.
200mm lens on Canon XSi, Verendrye airstrip, 0:01:46 to 0:46:00 EDT.