About J1012+5307
J1012+5307 is an epic pulsar. It spins once every 5.256 ms, has a dispersion measure of 9.02 pc cm⁻³ and carries a surface magnetic field around 303,604,537 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.