This is RCW 104, a faint (magnitude 18) emission nebula around the Wolf-Rayet star WR 75 in the constellation of Norma. This seems to be a very rarely imaged object, probably because of its southern location and very low surface brightness. I could only find four other examples on Astrobin, only two of which actually show the object! It took about 6 hours of OII subs to get any detail in the oxygen shell, compared to about 2 1/2 hours of Ha. There are a couple of hours of rgb for the stars.
Acquisition details and a link to a larger version are
here on Astrobin.