Our team at SRO first imaged this target in 2021 and thought I really liked the result, our mirror was dirty and the sky was full of California smoke. I inadvertently put this on the target list this year under a different catalog number not realizing it was the same nebula. Once I did realize it, the target was well underway and I thought it would be interesting to combine the 2021 data (what was usable of it) with the 2023 data.
Subframe Selector made it obvious just how much better the 2023 data was. Even though it's probably about 50/50 in mix the 2023 data has much higher weights and probably dominates the result in the integration. I was attracted to a similar look to the 2021 version but this one has lots more detail. They almost feel like two different targets to me.
Here's how it was processed:
Each S, H and O:
DBE
blurXterminator
starXterminator (extracting screened stars)
GHS (GH only)
SHO:
channel combination
histogram transformation (to align peaks)
LHE
Curves (contrast, color)
SCNR (removed about .67 green to eliminate green cast from hydrogen "haze")
noiseXterminator
MLT (mild sharpening)
pixel math in stars (screen)
dynamic crop to final framing
stars:
pixel math (r: H_stars, g: .8*o_stars + .2*h_stars, b: o_stars)
SPCC
GHS (gh)
unsharp mask (very mild sharpening)
The stars processing was an attempt to simualate RGB stars with narrowband data and comes from
https://www.cloudynights.com/topic/710701-how-to-produce-rgb-stars-or-close-to-from-narroband-data/. I'm not sure how much difference this made but it didn't seem to hurt.
Compared to the 2021 version (
https://www.astrobin.com/xmar6g/B/?nc=&nce=). This has more detail. The 2021 leans into the green and runs with it. I still like the 2021 version. It feels a bit abstract and where the green ended up wasn't obnoxious. In 2023 the green became essentially a color cast that didn't add to the image so I removed a good chunk of it which improved the clarity of the image. I like them both but for different reasons.
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