Coalsack Loop (UPDATE)

In search of the coalsack loop...a large but very faint ring of HII emission thought to be a supernova remnant. It was noted in 1979 but only first imaged in 1997 (see https://www.atnf.csi...alker/paper.pdf ).

I have displayed this inverted to try to match the original photo in Figure 1 and help see where to go (panels were positioned using Telescopius around Jewel box).

This image is a mosaic of 4 (now 6*) panels: In total I managed 3 hours of 6 min guided subs- battling 50% moon, low sky position and neighbours' cars- although that time is split unevenly top-bottom. I used the Samyang 135mm lens and ASI533MC (& MFT very fiddly adaptor) shot at f/2 with a fast ratio astronomik Ha 5nm filter. Vignetting at this f stop was calibrated out having first tried 10 min at f/2.8 and saw no difference. For reference the original 1997 photo used 15 min subs at f/4.5 and 1.5 nm filter.

*Latest: Added two more 1 hr panels at the top of this image where the loop turns to the right plus stars for reference; https://www.cloudyni...635_5994994.jpg

**Full final image of 9 panels- approx 10 hours altogether including broadband stars here:
https://www.cloudyni...35_33644187.jpg