Which famous star was observed exploding as a supernova in 1054 AD?

The famous star observed exploding as a supernova in 1054 AD is now known as the Crab Nebula. Ancient astronomers in China and other places saw the bright explosion in the sky, which remained visible for weeks, even during the day. Today, the Crab Nebula is studied as the remains of that supernova event. The explosion marked the death of the original star and the birth of the nebula, which is filled with glowing gas and a fast-spinning neutron star called a pulsar.