Hi David, the fuzz is almost certainly a ghost of the bright star at the center of the frame. I had a similar fuzz appear on a sequence of one of my comet image runs. After I had done astrometry on the fuzz and sent it to Nick James he ran the astrometry though FindOrb and the result was an ludicrous earth orbit object. So I suspect your fuzz will be the same, a ghost image of the bright star. Nice image of the comet though, please send it to me for the BAA Comet Archive. Denis
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