M 31 - also known as the
Great Andromeda Galaxy - is one of the most popular and photographed deep sky objects. Nevertheless, I decided to test my new equipment on this bright galaxy, and I must recognize that the results are quite outstanding. I didn’t expect to obtain so many details from a quite polluted sky (bortle scale from my site is between 6 and 4), with the crescent moon and with a mid-level APS-c DSLR (unmodded).
In M 31 galaxy several star clusters, such as NGC206, and dust clouds are clearly visible. Some interesting details are visible also in the cores of M 32 (the compact nucleus) and M 110 (the star clusters in the core and the dark clouds). On the background several faint and far galaxies are recognizable and the faint halo surrounding the three galaxies (in particular, the bridge between M 31 and M 110 and its warped halo).
I tried to emphasize the details in the galaxy’s arms and clouds without blowing out the core and hide the faint surrounding halo. Personally, I don’t like strong HDR processing, so I tried to balance the dynamic range of the signal between revealing faint details and keeping a natural-looking aspect.
Here’s my PixInsight workflow:·
- Preprocessing with WeightedBatchProcessing
- Integration with GESD
- DynamicBackgroundExtraction
- LinearFit on each RGB channel
- ColorCalibration and SCNR
- Noise reduction with TGV Denoise and MultiscaleMedianTransform (as described in https://www.lightvortexastronomy.com/tutorials.html)
- Stretch with MaskedStretch and HistogramTransformation
- Star reduction with MorphologicalTransformation
- Light HDR stretching on brightest areas (galaxies’ cores)
- Split stars and background with StarNet
Background and stars have been further processed with Topaz DenoiseAI (final noise reduction) and Pixinsight to enhance and balance colors and contrast. I am very happy about this image – considering it is a first light test – and I hope you will enjoy too. Clear sky to everyone!
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