Got to try my small Busack-Riccardi-Honders on a comet finally.
This was 40x120seconds with an old QHY8 camera. Darks and flats applied.
The first image is the full 3x2deg field. The second one is a roughly one degree field crop, at 100% resolution.
The ion tail is barely distinguishable.
I'm still getting stray light problems with the instrument. I will have to add a secondary baffle.
So beautiful. I hope to get a glimpse mid December up here on 54th North.
There's a gray, fuzzy circle at 11 o'clock, on an extended line from Witanen over HD 12475.
That fuzzy circle was not identified by nova.astrometry.net , though.
Zooming into your original stack, can you make out more detail? It doesn't look like an out of focus star, does it?
I have noticed that fuzzy spot on the very first sub I captured and kept an eye on it for a couple of hours. It did not move. This part of the sky is full of small galaxies, many of which can be easily recognised on the full frame/resolution image.
If you click on the second, cropped image, IIS should display it at full resolution and that spot is almost resolved into a spiral galaxy.