My first time playing with a comet. I tried various combinations at astrofest including some 3minute subs guiding on the comet, a few 60 second subs guiding on stars and combined them in all sorts of weird and wonderful ways.
Below are two attempts at processing, the one with sharp stars involved a little photoshop cheating but hey I'm no saint :-)
Larger versions are available here:
Startrails 6.8MB
Sharp stars 3.7MB
I also learnt that guiding on a comet works right up until the point where the comet passes a star.