[Stevec35 (Steve)]

Originally Posted by DavidU

Very nice indeed !

Thanks Dave

Originally Posted by Placidus

Hi, Steve,

Good work with the SII. What it seems to be saying to me is that although the SII is brightest where there is the most stuff, e.g. near the keyhole (you can't have SII emission without sulphur), the place where it is brighter relative to H-alpha is way out in the suburbs, where the gas is extremely thin, and the SII forbidden transition (which struggles to occur in dense material because it is prevented by thermal collisions) can happen unimpeded. So new information compared with just H-alpha and OIII.

Best,
Mike

Thanks Mike. Yes the SII adds interesting depth that the previous image didn't have.