This is a three-year-old image. The imaging was done between 2014 and 2016 over many nights. The initial processing was completed a year later and can be found here:
https://www.astrobin.com/298047/C/In this reprocessing, I increased the level of contrast stretch to bring out more faint nebulas. This was not possible in the 2017 processing because more stretching would only amplify the imperfectness in flat-fielding, sky gradient removal, and star colors. The star color issue is caused by slight focus differences among the mosaic frames and the focal plane tilt of my camera. These lead to stars slightly in and out of focus in different areas of the image, and thus different color fringes. This is very subtle, but can prevent strong contrast stretches.
Now, with my improved processing skills, and with the very reliable star removal provided by Starnet++ (kudos to Nikita Misiura), it is possible to more clearly examine the residual sky gradient and color variation across all the mosaic panels. The better corrected color and background, though still not perfect, allow me to apply stronger contrast stretch to bring out the faint nebulas. And this is the result.
The original image has about 390 mega pixels. The version uploaded here is a 50% reduction. A 66% reduced version can be viewed on
Gigapan.
Here is an animated version for you to try.
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