Gamma rays from the Crab Pulsar 0531+21

Results are reported for observations of PSR 0531 + 21 performed with a gamma ray double Compton scatter telescope launched on a balloon. The operation of the telescope and the handling of the data are described. Phase diagrams for the pulsar and energy distributions for gamma rays from the primary and secondary pulses are shown and discussed. The results indicate that these observations are the first of gamma ray lines from neutrons captured on protons or iron in pulsars. Arguments supporting this interpretation are given.