Thanks for the help all. My camera is a Canon EOS 5D mk3, so 36 × 24 mm full-frame cmos sensor. I certainly haven't touched the primary mirror yet and I hope I don't have to
Here's the full image:
https://drive.google.com/open?id=1C2...BNbsGejZPxGf-g
This was ISO 800 and 2 minute sub