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Hi, Rodney,
An adventurous undertaking. The H-alpha is looking promising.
A bit like RCW 104 in Norma, the problem is not so much pulling out the OIII and SII from the noise, which you are already doing; it is seeing it against the stars, which become brighter and more intrusive with further exposure.
When doing RCW 104, we could see something in the SII image, but it looked to be exactly and precisely the same as the H-alpha image, making us wonder whether what we were seeing was just leakage of H-alpha through the SII filter. We gave up on the SII, not convinced that we were really photographing SII. All we had really shown was that if there was any, it was a ridiculously faint ghost.
Perhaps in view of the difficulty of pulling OIII out from the starry background, you could do what Rick suggested for us, and present the H-alpha and OIII as two quite separate images to be compared side by side rather than trying to combine into a colour image. I would just skip the SII.
It is very good to see difficult targets being investigated.
It seems typical for both PN's and some WR's for the OIII to be less extensive than the H-alpha, because the sufficiently hard UV from the central star has been used up before the softer UV that stimulates H-alpha emission has been used up. Similarly the OIII emission seems to be often more featureless, perhaps because the gas that is emitting H-alpha was emitted earlier, has gone out further, and is colliding with pre-existing material, causing visual detail due to shock fronts. You are seeing both those things happening here, as we did with RCW 104.
Good work.
Best,
Mike
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