X-rays from giant radio pulses Pulsars are spinning, magnetized neutron stars that are observed as a regular sequence of radio pulses. Most pulses are of consistent intensity, but occasionally one is brighter by orders of magnitude. The cause of these unpredictable giant radio pulses (GRPs) is unknown. Enoto et al. observed the Crab Pulsar simultaneously with x-ray and radio telescopes. They found that x-ray emission during GRPs was slightly brighter than that during normal pulses. Comparing the radio and x-ray enhancements provides constraints on the GRP emission mechanism and the possible connections with other transient radio phenomena. Science , this issue p. 187