This artist’s impression shows a supernova and associated gamma-ray burst driven by a rapidly spinning neutron star with a strong magnetic field — an exotic object known as a magnetar. Observations from ESO’s La Silla and Paranal Observatories in Chile have for the first time demonstrated a link between a long-lasting burst of gamma rays and an unusually bright supernova explosion. The results show that the supernova following the burst GRB 111209A was not driven by radioactive decay, as expected, but was instead powered by the decaying super-strong magnetic fields around a magnetar.