RCW 104 in H-alpha (yellow) and OIII (blue). It is difficult to show these two together in the same image, as the OIII is very faint compared with either the H-alpha or the starry background. H-alpha 5 hrs, OIII 10 hrs, all in 1 hr subs. Aspen CG16M on 20 inch PlaneWave

RCW 104HalphaOIIIhydrogen alphaoxygen III