Sh2-216 "The Second Planetary Nebula" and SH2-221

Extremely faint objects, especially for winter and an orange light pollution zone. A dual-cannon setup on a single mount. 1. Askar SQA55 55mm f/4.8 telescope with a Touptek IMX571 C camera and an Optolong L-Ultimate filter. 2. Samyang 135mm f/2.0 ED lens with a QHY5III585M camera and a Touptek AFW 8×1.25" filter wheel. I tried to synchronize the two scopes, but after losing a night, I realized it was nonsense—the cameras wouldn’t wait for each other. So, I ran one with 10-minute subs and dithering every 3 frames, and the other with 5-minute subs, ending up with about every 6th frame from that camera in the trash. Now about the object—it’s on AstroBin but not here. Sh2-221 (left) is a supernova remnant located about 2,600 light-years away from the star that exploded roughly 6,000 years ago. Its diameter is about 130 light-years. The star, once very similar to our Sun and which created the planetary nebula Sh2-216 (right), began slowly dying half a million years ago, making it ancient by planetary nebula standards. Sh2-216 is much closer, about 400 light-years away, and significantly smaller—11 light-years in diameter. It is the second-closest known planetary nebula, as well as the largest and oldest. The yellow-orange patch above Sh2-221 is Sh2-217. It is part of a larger star-forming region and contains about 4,100 solar masses of material. The star-forming region mentioned above is very young for such objects, only 4 million years old. Sh2-217 is about 13,700 light-years away and spans about 35 light-years at its widest point. The smaller object Sh2-219, which appears to sit on the right shoulder of Sh2-221, is part of the same star-forming region as Sh2-217 and lies at roughly the same distance from us. The emission nebula BFS 44/LBN 755 in the lower part of the frame between the two large objects is also part of the same star-forming region. Just a couple of nights so far—I’ll keep collecting more data.