Here's my go at the Horeshead. Over 2 nights 19 & 20 Jan (chucked the 2 hours of subs from the 18th as of a focusing stuff up, or lack thereof).
Nearly 6 hours of 90sec subs on ASI071Pro with GT81 refractor.
Captured with APT. I tried dithering and I think it worked, but not sure of the parameters yet.
Processed in PI. For calibration files I only used bias frames, no darks. Tried drizzling - wow they are big files! I'm still getting blotchy backgrounds with my processing - maybe I'm overcooking it? Tried TGVdenoising.
More detail on
https://www.astrobin.com/330285/0/
Why does Alnitak spread so much. Is it a reflection of the object, or is limitations of the scope / camera ??
Thanks for looking, Chris