NGC 602 is an open cluster at the edge of the small Magellanic cloud, surrounded by some faint nebulosity.
9hrs of OIII, 2x2 binned in 1hr subs to get the truly faint stuff. Note in particular the large but extremely faint super-bubble about 30% of the way to the right of the central brightest region, and an even more tenuous, somewhat larger super-bubble (asymmetrically around its own conspicuous open cluster) about half-way toward top left from dead centre.
Original image here.
The super-bubbles are not visible in H-alpha. Combining to produce an H-alpha OIII image tends to hide the faint OIII images. There is virtually nothing to see in SII, making it perhaps less likely that these bubbles are supernova remnant material, as opposed to pre-existing material, although that is a guess.
Cheers,
Mike and Trish