M81 (A very long progression)

[Italianmoose0]

I've been lurking for a long time, but I've finally got an image I'm happy enough to post! M81 was the first galaxy I ever spotted for sure, back in my "point the telescope at the sky and see what's there" days. It's also one of the first I've tried to image so I have three images from three different equipment phases. First was a barlowed 130P newtonian, which I later modified to shunt the mirror forward so I didn't need the barlow, with a 5D mk2. Then moving to a reduced GSO RC6 with a much better field. And finally adding a cooled 1600MM. It's very satisfying to see the jumps in quality.

Thank you for all the helpful stuff you've posted

The final image is made up of:

• ~200 Luminance
• ~100 each of R, G, B
• Slight dithers after every 5 images

All at 60 seconds, -15C, guided, with dark, flats, and flat darks from library. I've not been brave enough yet to go beyond gain 139 on the ASI1600, I've only just really settled on the exposure time. Then stacked in DSS, composited in SIRIL, and tweaked in Affinity photo. I also did some very experimental noise reduction with Python, not sure if it was particularly useful. I've found a very slight gaussian blur before using noise reduction to be very helpful in improving the output. This is rather oversampled so you don't really lose much in quality to gain improved smoothness.

Also lesson learned, always check to see if the star you're focussing on is a double or not! Doesn't half mess with you.