### Update 10th Jan 2023 #########################

The past 7 weeks of cloudy weather motivated myself to reprocess some old data. I tried some new processing techniques regarding sharpening and stretching. Here is a before/after comparison gif of some details:


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I am finally back and finished two more projects. NGC 6888 "The Crescent Nebula" is my first narrowband DSO. I processed the HOO data in APP to get a first feeling of this line of astrophotography... and I love it

The fact that NGC 6888 lies in a dense field of the Milky Way, makes it a perfect candidate to test collimation, backfocus and tilt, because you have a lot of stars up to every corner. I finally improved my collimation, thanks to a piece of cartboard with a hole (it took me long enough to realize that this simple gadget allows me to focus on the roundness and centering of the secondary mirror at the same time!). But I still had problems with tilt and backfocus. But steady we go.

I also recorded RGB for the stars (60min each), but heck... i don't manage to keep the spikes with me when I want to replace the NB stars with RGB stars... Sinc this is just a first test of HOO processing, I'll try the RGB stars on my next project.

NGC 6888 - "Crescent Nebula"[1]The Crescent Nebula is an emission nebula located in the constellation Cygnus. It has an apparent magnitude of 7.4 and lies at an approximate distance of 5,000 light years from Earth and about 26 light years across. The star responsible for the nebula’s shape and glow is the Wolf-Rayet star WR 136 (HD 192163). The nebula is formed by the star’s fast, powerful stellar wind that collides with the slower wind ejected by the star about 250,000 years ago, when WR 136 expanded to become a red giant. The collision has produced a dense shell, which continues to expand at a speed of 80 km/s. A shock wave is moving outward from the shell and producing the filamentary structure visible in images, while another one is moving inward to create a bubble of gas that is heated to X-ray emitting temperatures.
WR 136 will likely end its life in a supernova event within a few hundred thousand years. Its estimated age is about 4.7 million years. The star is 3.3 times larger than the Sun, 15 times more massive and 260,000 times more luminous. It may be a binary star with a low-mass companion of spectral classification K or M.