Short gamma-ray bursts — instantaneous, but most powerful explosions — are born from the mergers of neutron stars (the superdense remnants of dead stars). Sometimes after the collision, a rapidly spinning magnetic top remains — a magnetar, whose field is billions of times stronger than anything that can be created in a laboratory.
Sifting through data from a 90s satellite, scientists stumbled upon the flash GRB 960616. It lasted only 30 milliseconds, but its gamma radiation pulsated 1100 times per second — like the feverish heartbeat of a cosmic body. The rhythm signature stood out especially clearly in the hardest gamma rays, revealing the spin of a recently born pulsar — a lighthouse star, whose beam scratches across space 1100 times per second.
Each rotation of the star fits into 0.0009 seconds — a moment in which light can travel only 270 kilometers. Such a discovery is only the second case so far where a gamma-ray burst reveals the pulse of a newborn magnetar. By hunting for such signals, astronomers will be able to measure the spin of the most distant and fastest cosmic 'spinning tops'.
During those same 30 milliseconds that the flash lasted, Earth barely noticeably wobbled, while the neutron star made 33 full rotations.