IC 5148 is a planetary nebula in Grus (the crane), aka the “Spare Tyre Nebula”. It is about 3000 light years distant and estimated to be expanding at 50 km/sec. The bright core region is fairly small — about 2×2 arcminutes. Most amateur images only show the core, but we have aggressively processed the narrowband in this image to display the extended shell. The shell mainly glows in the light of doubly ionized oxygen (OIII), especially its inner and intermediate portions, but there is a more peripheral hydrogen alpha component as well, seen as dimmer zone with a slight purplish color (due to the combo of Ha & OIII) — this most noticeable at about 1:00-2:00, but also slightly at the 5:00 position.
Imaged at SWOS in El Sauce, Chile in 2022 using a 24″ Planewave CDK @ f/6.5 and SBIG STX-16803. Image scale 0.47″/pixel with 15 hours RGB, 9 hours Ha, and 13 hours OIII. Processing was via a collaboration with Mark Hanson.