This is only nine exposures of 32 minutes each binned X2.
A great deal of care was taken with darks and bias to make sure they did not introduce noise.
This is the drizzled image.
https://www.flickr.com/photos/343863...in/dateposted/
By the way when binning X2 you only get one quarter of the read noise.
It helps to have at least one hundred bias frames and about seventy dark frames. It also helps to download at the slowest speed for your camera.
Bert