This is a 2 by 1 mosaic of the Andromeda Galaxy, with data captured over 2 consecutive nights early October. A project I've had in mind for a long time!
It was a challenging one:
- My mount experienced guiding errors, mostly the first night. The RA axis seemed to go nuts periodically and I had to throw away about 25% of the subs. I switched back from the OAG to a 50mm guide scope, and the problem seemed to go away for some reason...
- Strong gradients from Nantes' light pollition, as well as the last quarter of the Moon
- Colors and gradients for the 2 panels were slightly different, which makes creatig a mosaic more difficult. After a few attempts though, and with the help of some tutorials, I managed to find the right settings
- Blowing up the core of the galaxy while stretching is easy. I tried a new approach for stretching: 1) a slight stretch with ArcSinhStretch, 2) a Generalized Hyperbolic Stretch and 3) a few adjustments via curves & histogram. Lots of trial and error but overall the core doesn't seem too blown out!
- I finally switched from DeepSkyStacker to PixInsight for calibration and stacking. PI is so much slower... but the resulting image seemed easier to process, especially gradients, presumably due to the local normalization
- I'm still learning PixInsight, so every processing is a challenge! However I did learn a few helpful tricks, and I hope to remember them for my next processing.
But as always, despite the frustration and the hours spent working on this photo, I am very pleased with how it turned out! Definitely my best astrophoto so far.
Another reason why I love Andromeda, is because it was the first target I photographed when I started AP in 2017. I'll never forget the joy I felt seeing for the first time a galaxy on my camera's screen! It is always fun to measure the progress I've made over the years, and it definitely motivates me to keep on learning!
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