Overview
The remains of a star that exploded as a supernova approximately 15,000 years ago.
Background
This was a tough image to edit, and I ended up restarting from scratch three times until I settled on something I was happy with.
The supernova remnant has a lot of green data in the integrated image — both within the structure of the gas that I wanted to look prominent, and also the background noise that I didn’t. Initially I tried keeping the remnant’s green in while removing the noise, but couldn’t get it looking good. Eventually I gave up and went with the nuclear option (PixInsght’s SCNR function to remove all the green). This smoothed out the background, and flipped the green in the gas to be more blue — which, happily, I like the look of.
I also had a tough time evening out the background. I tried a lot of different things, including loading the image in Photoshop and using Gradient eXterminator. Eventually I found that PixInsight’s AutomaticBackgroundExtractor (ABE) with the function degree setting set to three did a good job.
The framing was very tight around the entire Cygnus Loop, so I cheekily did a bit of Photoshop work to expand the canvas size and clone in more stars. This gives more “breathing space” around the edges of the photo. If I ever get a reducer for my telescope, I could have another go with a lower focal length and so avoid the need for that bit of cheating. I think the image would also benefit from a longer integration time (this is 15 hours) but the weather forecast is terrible and I want to wrap this one up!
When editing, I couldn’t help but notice that part of the Loop looks like a xenomorph head. See what I mean?
Imaging details
| Date | August & September 2021 |
| Location | Bristol, UK (Bortle 8) |
| Telescope | Askar FRA400 f/5.6 Quintuplet APO Astrograph |
| Camera | ZWO ASI 2600MC-PRO |
| Mount | Orion Sirius EQ-G |
| Guide | William Optics 32mm; ZWO ASI 120MM Mini |
| Control | ASIAIR Plus |
| Software | PixInsight, Lightroom |
| Filters | Optolong L-eXtreme (Ha/OIII): 450 x 120 seconds |
| Total exposure time | 15 hours |
| Image credit | Lee Pullen |
Source data
Seestar S50
Seestar S50 image coming later…
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Definitely a xenomorph head!
I know, right! Now you’ll never be able to see it as anything else 🙂
I am editing my image of the Cygnus loop taken with a Samyang 135 and a ASI533MC Pro with a L-extreme. I feel for your editing pain. I had the same issues and used SCNR for the same reasons. I also used GraxPert to get rid of the unneeded red background. My challenge is integration time. Mine only has 70 subs = ~ 2 hours. Will add much more and see if I can bring up the fine detail between Pickering’s Triangle and the Eastern Veil.
Good luck, it’s a surprisingly tough target!