Pulse arrival times (timing residuals)
Rotation frequency & glitch events
Neutron stars pack 1-2 solar masses into a 10 km radius — nuclear density, where neutrons touch. Pulsars are cosmic lighthouses: spinning magnetized neutron stars with radio/X-ray beams sweeping at 0.0016 Hz (Crab) to 716 Hz (PSR J1748−2446ad). Glitches are sudden spin-ups from superfluid neutron vortex avalanches coupling angular momentum from the crust superfluid to the solid crust. Magnetars have B ~ 10¹⁵ Gauss — the strongest magnetic fields known — powering Soft Gamma Repeaters that release more energy in 0.2s than the Sun emits in 100,000 years.