I knew I had to take this photo when I saw it on astrobin (https://www.astrobin.com/x5mclj/).

I'm just starting to learn PixInsight and I didn't manage to replicate the above stunning result.

In the end, out of the many encountered problems, the main is the star bloat. However, I've been working on this image for too long now, and it's time to stop. Maybe I'll return to this data in the future.

I collected the data over 4 nights in Bieszczady mountains (Bortle 2), but the moon was in 3rd quarter. In total out of over 10 hours, 7.5 hours were used (5 minute exposures).

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Acquisition:

* ISO 800

* Lights: 5min x 87 (7.25h)

* Flats: 1 Synthetic (see notes) Darks: 12

* Bias: 0 (100) (see notes)

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Equipment:

* DO-GSO Newtonian 150x600

* Sony Alpha 5000

* Baader Moon & Skyglow 1,25" filter (see notes)

* Skywatcher HEQ5

* Guiding: StarGuider 50/162 + ZWO ASI 120MINI

* PowerTank Lithium Pro

* Raspberry Pi 4B + Astroberry setup

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Processing:

Main work in PixInsight:

* Took more than 2 weeks (multiple evenings). Very steep learning curve.

* Overall, followed this tutorial https://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html

* LocalNormalization used to combine data from multiple lights and occasional gradients

* Aggressive DBE was used to remove remains of vignette "ring" (see notes)

* Synth flats: http://trappedphotons.com/blog/?p=756

* Color calibration: https://www.lightvortexastronomy.com/tutorial-colour-calibrating-images.html

* Star reduction: https://www.lightvortexastronomy.com/tutorial-reducing-star-sizes.html

* Stretch: https://www.lightvortexastronomy.com/tutorial-stretching-linear-images-to-non-linear.html#Section3

* Noise reduction: https://jonrista.com/the-astrophotographers-guide/pixinsights/effective-noise-reduction-part-1/, https://jonrista.com/the-astrophotographers-guide/pixinsights/effective-noise-reduction-part-2/, https://jonrista.com/the-astrophotographers-guide/pixinsights/effective-noise-reduction-part-3/

Adjustments in LightRoom:

* Vibrance, noise reduction, also some linear and radial gradients in some strategic locations (heresy, I know, but I'm still learning PixInsight)

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Notes:

* Flats: I took them against with T-shirt the sky - this produced a linear gradient and I had to throw them out. In the end, created synthetic flats using http://trappedphotons.com/blog/?p=756

* Bias: I had many issues calibrating frames in PixInsight, and in the end I didn't use Bias, as they made vertical banding worse.

* 1.25" filter - produces way too much vignetting against ASP-C in the camera. Will have to switch to 2" filters, because fighting with flats is very annoying.

* DBE and BackgroundNeutralization were abused throughout this project and I think the result is still subpar (there are color blotches all over). I think this stems from bad flats, so I hope I won't encounter this issue in the future.