The central star in this complex is an O class of ~40 solar masses. It is nearing its end of life, and has been subject to mass loss events (something like Eta Carinae?). It is thought to be destined to end as a supernova
The dumbell-like inner shell has the two designations: NGC 6164 and 6165.
The very faint outer shell - mainly OIII - is only rarely imaged, as it is extremely tenuous.
This image was shot with ASA10N at f/6.8; Moravian G3-16200; DDM85 unguided. 2hr40min OIII, 2hr30min Ha, 1hrRGB all binned X2, as I was prepared to sacrifice resolution for photons. The image structure is essentially Ha to red, OIII to green and blue, RGB star colours.
Having processed it, it is clear I could use another 4hr OIII to advantage, so it is a work in progess
Excellent! You're picking up unbelievably faint hints of OIII in the outer shell toward 2 o'clock which didn't show up when we did it unbinned. We're going to have to do it all again now.
Thanks to all for your comments. Very much appreciated.
Chris, it was shot from the north side of Macedon near Hanging Rock. I don't know how well the very faint OIII areas would show from Melbourne. As it was, the OIII stack was quite noisy with a reasonably dark sky (SQL 21.3), whereas the Ha was very clean.
Not sure when I'm going to get the extra OIII - this dark time looks unprospective, so it's probably a month away.....
That's really nice!
I had been wanting to image this this new moon, doesn't look like that's going to happen :/
With some more OIII some of that fault stuff will come up a lot cleaner