I took this a few weeks ago and only got around just now to processing it.
This is 2 hours and 48 minutes. I actually have more data so another version is on its way. I believe I have around 7 hours of data which would make it the longest comet image I am aware of.
I developed my own processing system for this. It may not be totally perfected yet but certainly workable. I think I can get a better result in the 7 hour version.
I'll have to check up on the comet to see how it is going now. It seemed brighter when I first imaged it. Perhaps it has brightened again now.
http://www.pbase.com/gregbradley/image/138119382
Greg.