Crab Pulsar Reference Libraries
Crab Nebula -- The Crab Nebula (Messier 1, NGC 1952) is the object the which started Charles Messier logging non-cometary objects on his Messier Catalog. It is the expanding cloud of gas thrown off in the explosion that gave rise to the 1054 supernova recorded by Chinese astronomers, now more than 6 light years across (the nebula is currently expanding at 1000 km/sec and the total mass of...
- The navel or umbilicus.
- In Greek archaeology: A central boss, as on a shield, a bowl, etc.