After all the fuss and hyperbole and general excitement in the astronomy press, I finally managed to get a 5am clear sky and have a go at comet C/2012 S1 (ISON), using my newly-acquired (but about fifteen years old) Nikkor ED 300mm f/4. This lens is autofocus, so no reassuring “thunk” as the focus ring hits the infinity stop. On the other hand, it fixes focus on first-magnitude Altair!
The standard for this session was six frames of 60 seconds for all shots. I also took a set of dark frames, flat frames and bias frames, and had a play with the processing suite PixInsight, which I’ve downloaded for a 45-day trial. More of that later.
ISON is in Leo, next to Mars, and still invisible to the naked eye. I couldn’t resist a little cheer when I saw this in the camera display. The stars are trailed because the six frames are stacked by aligning on the comet.
Most pictures benefit from a little cropping, and this is no exception.
A bit more crop and slightly more aggressive processing, still looks okay. The tail is tinged with green as the icy comet sublimates and releases cyanogen, emphasised by Mars’s red hue.
Still in Leo, Comet 2P/Encke is a few degrees to the north.
Comet C/2012 X1 (LINEAR) is only a few degrees away too, in the constellation Coma Berenices.