PIPP: auto-crop and analyse to select best frame from 40
GIMP: Convert to monochrome, using red and green channels only, adjust exposure, contrast and brightness, then sharpen final result.

The Moon just before dawn, showing 39% waning phase.

This morning at 07:15 the sky was covered with thin cloud and was very hazy, with the Moon being surrounded by a bright nebulous haze as seen in the inset in the main photograph. Things did not look too promising, but I needed an image of the Moon for my current project, so I set up anyway, hoping for the best. After acquiring 40 images, I could see it was not going to improve, so I processed what I had, using PIPP to find the best image to work with in GIMP. It was immediately obvious that I was not going to get a good colour image out of the data, so I converted it to monochrome using the mono mixer function, where I could adjust the contributions from the red, green and blue channels. Knowing that Rayleigh scattering of light affects shorter wavelengths (violet to blue) the most, I first dropped out the entire blue channel, leaving just red and green data for my image. I lost very lttle detail on the Moon, but all of the haze in the image disappeared, so I had no need to drop the green. A little tweak of the exposure to bring the brightness up, then adjusting the contrast curve produced an acceptable final result for sharpening. It was never going to be the best image of the Moon, but it demonstrates what is possible, even under adverse conditions.