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Ancient apocalypse

Kfir Simon, taken from Tivoli farm, Namibia

In the year 185 C.E., Chinese astronomers recorded the appearance of a “guest star” near Alpha (α) Centauri that remained visible for 8 months before fading — the oldest recorded example of a supernova. Astronomers now think that the faintly glowing shell of RCW 86 — a fragment of which is imaged here — is the remnant of that event, caused by the self-conflagration of a white dwarf. The imager used a 24-inch scope at f/4.5 to take Hα/OIII/RGB exposures of 180, 120, 20, 20, and 20 minutes, respectively.