it was so bright that Chinese and Japanese astronomers recorded it as a “guest star” in the Cassiopeia constellation. Now, astronomers using the Keck Cosmic Web Imager, or KCWI, at the W.

When a supernova was seen glittering in the night sky for six months in 1181, it was so bright that Chinese and Japanese astronomers recorded it as a "guest star" in the Cassiopeia constellation ...

It also reveals a new set of familiar star patterns littering the sky with ancient constellations. A good one to start with is Cassiopeia which is shaped like a big W or M with five bright stars.