0.01 second exposure, SBIG ST-4 CCD.
12" f/18 cassegrain telescope at prime focus.
Mercury can be a very frustrating planet to observe. Even at its best it is never far from the Sun. This is especially a problem when observing from within a dome, as many do not allow observations below about 20 degrees! Even at the bes tof times, Mercury is never more than 28 degrees from the Sun, to the opportunities for a dark-sky imaging session are extremely limited. To date, I have only imaged Mercury once with a CCD, back in 1998. I did hope to get some more images of it while I was in Australia during June 2007, as at that time, all of the planets (including Ceres and Eris) were visible. My plan was to image all of them during the course of one night. Unfortunately, Mercury was already below the rim of the dome once darkness fell!
