About J1815+5546
J1815+5546 is an uncommon pulsar. It spins once every 426.844 ms, has a dispersion measure of 59 pc cm⁻³ and carries a surface magnetic field around 2.03×10^11 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.