3C 400.2 (SNR G053.6–02.2) in Sagitta
3C 400.2 is a medium sized supernova remnant with a size of 16 arcminutes in the constellation of Sagitta, which optical parts have been found on Mount Palomar red plated by Sidney van den Bergh in a systematic search published in 1978. The distance is estimated between 12’000 and 20’000 lightyears.
Deep Ha exposure was required to reveal the structure of this nebula. North is up in this image.