About J0621+2514
J0621+2514 is an epic pulsar. It spins once every 2.722 ms, has a dispersion measure of 83.63 pc cm⁻³ and carries a surface magnetic field around 263,066,460 G.
The collapsed core of a star that exploded: about one and a half Suns of matter crushed into a ball the size of a city, held up only by the refusal of neutrons to be squeezed further.