Sh2-101, also called the Tulip Nebula, is a pretty H2 emission nebula with a nice mix of OIII and SII that allows significant structure to be revealed with SHO mixes. The more demure but exotic object, however, is Cygnus X-1. This is a binary system comprised of a super giant star and a similarly sized black hole separated by 0.2 astronomical units. This systems period is a mere 5.6 days! A large but faint blue shockfront is seen, however research by [P. H. Sell, S. Heinz, E. Richards, T. J. Maccarone, D. M. Russell, E. Gallo, R. Fender, S. Markoff, and M. Nowak] suggests it is actually a disk we are only seeing a portion of.

You can find the article here: https://academic.oup.com/mnras/article/446/4/3579/2892401. Thanks to Steve Milne for the link.

I would like to see the shockfront more prominently blue as we do in Steve's excellent image, but I was mostly focused on differentiating colors and structure in the Tulip itself. The SHO data was combined using Ludo's excellent Pixinsight dynamic narrowband combination process. This is a way to combine SHO masters in Pixelmath using stretched OIII data to determine the blend at a pixel level. In essence, where OIII is strong you get one mix and where OIII is weak you get another. Of course that varies smoothly as the OIII strength changes. This produces almost RGB like star colors (my image is pure SHO) and lots of separation of structure.

The Ha component of the shockfront is surprisingly strong so that may have been why it is not a bright blue here.

Here's the link to Ludo's process: https://thecoldestnights.com/2020/06/pixinsight-dynamic-narrowband-combinations-with-pixelmath/

The subs were particularly sharp. The median sub was 1.75" FWHM and some down to 1.3". For the Summer, where we get great seeing at SRO, I have been using the QHY600M bin 1 or .30" image scale. This is oversampled but I am definitely getting lower FWHM's than I did with 2x2. However, I reduced resolution of the final image to 2x2 since the mean FWHM was about 6 pixels before binning down in processing.

I did a light noise reduction using the old Topaz de-noise 5.1. This is the non-AI version. I've found that these days the word Topaz is a loaded term! I actually prefer the old non-AI Topaz for noise reduction since the AI seems to be more of a sharpening tool. That noise reduction was applied mostly to the background via a luminance mask.

A little sharpening was applied via unsharp masking at a 5 pixel scale. This was done masking out both the stars and the background.