This is my Summer 2021 project.

Adquisition Notes:
I imaged from my backyard, so the adquisition itself was really effortless. Images where taken from 01/08/2021 to 27/08/2021 (27days). First nights there were some dew, but fortunatelly not enough to affect the lenses. Was able to image 12 session out of 27 days, gathering 38h of integration time. Lost sessions were due to bad weather, full moon, or days that I simply was doing another things.

Processing Notes:
The main goal of the project was to explore if there was a "hidden" shell inside the supernova. I have found many unseen (as far as I know) structures but can't assure which of them are part of the supernova or which belongs to the OIII background nebulosity because I didn't found any deeper image of this object and also not much literature about it. Any help on this subject will be welcome!.

Taking this into account I decided to not to isolate and push up the supernova, so I pushed also the OIII background. The result, in my opinion, is a nice representation of the interactions between H and OIII emissions. 

Here the processing, more in detail:

OIII:
Very faint object on OIII so I had to work hard on the noise reduction on this channel. After the typical starting processes (DBE,crop,mure) I applied StarNet to work with the isolated nebula. I applied 5 noise reduction steps, being very careful to not to destroy too much detail. Finally, an HDR application, to resolve the brighter parts of the nebula.

H:
Same workflow but the H emission was quite strong, so there were good SNR, so I could clean the data with a very minor noise reduction application (1 step of ACDNR).
Apart of this, the HDR application was more agressive to avoid to overwhelm the OIII data.

HOO Combination:
Channels where combined using H/90%OIII+10%H/O, so almost pure HOO. This little 10% of H added to green added some structure to the H data.
Then I applied curves for tonemapping and saturation.
Finally I added the calibrated narrowband stars back following my methodology (https://aiastro.wordpress.com/2020/06/02/rgb-stars-from-narroband-data/) and pushed up the supernova with a blurred mask.

Refining process:
You would probably note that the processing has been quite simple, and this is because there were an very deep refining process, as deep as you may notice that it is version CN. I think that I have made more than 200 versions, in about 2 weeks, thank to the use of Process Containers, a procedure that I encourage everyone to use. You can find more info on my tutorial here (https://aiastro.wordpress.com/2021/03/10/projects/)