M31 - The Great Andromeda Galaxy

This is the first of several images that I took at Lake San Antonio. Originally we wanted to go to Likely Place, but the wildfires destroyed the awesome dark skies up there :-( Lake San Antonio isn't super dark, but considering that it it just 2+ hours away from us it is pretty good.

(click on image for full resolution)

I n order to bring out the core, I used two different exposures: 600s/450sec and 60/45sec (for 1x1 and 2x2 binning). I used the tutorial from Light Vortex Astronomy - which was very good as always. In the end, it didn't make a huge difference. I probably should have rather taken only long exposures to get the faint details in the outer regions. In addition, I took Ha images after we returned home to bring out the nebulae.

I had to fiddle with the sequence of processing:

1. Calibrate, align and stack the individual exposures (I ended up with 2 sets of LRGB images and one Ha image)
2. Remove Gradients with DynamicBackgroundExtraction
3. Combine the two different exposures with HRDComposition
4. Combine the RGB images with LRGBCombination
5. BackgroundNeutralization and ColorCalibration of the RGB images
6. Folding in the Ha data
7. BackgroundNeutralization again (the background was on the red side after folding in the Ha data)
8. then processing as normal

Processing was surprisingly difficult. I assumed that processing images from the RH200 scope under dark skies would be easy. But the background gradients were surprisingly strong.

As many astrophotographers, M31 was one of the first images I ever took:

Amazing what difference 6 years of experience (and a lot of $$$ for better equipment) make :-)