About J1048+2339
J1048+2339 is an epic pulsar. It spins once every 4.665 ms, has a dispersion measure of 16.65 pc cm⁻³ and carries a surface magnetic field around 379,056,741 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.