About J1523-3235
J1523-3235 is an uncommon pulsar. It spins once every 1,504.835 ms, has a dispersion measure of 72.3 pc cm⁻³ and carries a surface magnetic field around 1.21×10^12 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.