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Thanks guys.
Bert you are right in that I reduced the green channel markedly to produce the hubble palette. The resultant by product is these magneta stars. Many Hubble images have them. To get around the issue RGB stars can be masked in over the narrow band data. The filter option might be possible as I have one spare filter space left.
Mark, if you read my initial post I say that it needs two more sessions yet to get the noise down. I fully agree there is a lot of noise. I used scale darks which could have contributed to the noise but will use same time darks for the next run. This is 7 subs per channel but I think given the dimness of the target it probably needs something like 21 in each channel and maybe even more in the OIII data. I am currently collecting data on several objects and all with narrow band data. Just running this one around a bit. Next time the image will have a marked improvement.
The Halos are most likely from defective filters and not CA. An Apo from Takahashi is not known for CA. I bought the filters second hand those might have been from an older batch that had problems with halos. Astronomiks were replacing those filters. I am tempted to get them replaced under the original agreement. It depends on whether the company will play ball on this. Replacement with RGB stars will make a huge difference to the look of the image.
James you picked it. This data was stretched twice to pull out this detail.
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