The Crab Nebula (M1, Messier 1, NGC 1952, Tauras A) is the results of a Supernova (SN) recorded in 1054. The nebula was discovered in 1731 with an Apparent Magnitude (m) of 8.4 and invisible to the naked eye. In the center is a Pulsar (PSR) with a pulse Frequency of 30/second.
The Crab Nebula has been much studied, being useful in gathering data and testing models. For example, when pulsars were first discovered, it was predicted that a pulsar would be found in the Crab Nebula and it was, helping confirm the model that pulsars are spinning Neutron Stars formed from supernovae.