High energy observations of pulsars

High energy emission have so far only be definitely observed from two pulsars: Carb (PSR 0531+21) and Vela (PSR 0833−45). In these sources, however, the luminosity at gamma‐ray energies surpasses the radio luminosity by approximately 106 which demonstrates the basic importance of this emission for the pulsar radiation budget. Deep observations performed with the COS‐B instrument in the 0.1 to 1 GeV gamma‐ray energy range have revealed several previously unknown details: The Vela pulsar gamma‐ray spectrum changes with light‐cure phase such that the second peak of emission exhibits a harder spectrum than the first peak. In the Crab pulsar a secular change of the relative strength of the two peaks of emission has been detected with high probability in the course of observations spread over 5 years. It is remarkable that concurrent observations of the x‐ray (1−12 keV) pulse profile of Crab do not show this variaiton. The search for gamma‐ray emission from further radio puslars has up to now been inconclusive. From the estimated further radio pulsars has up to now been inconclusive. From the estimated flux limits it is however possible to derive limits to the contribution of pulsars to the high energy luminosity of the Galaxy. It is expected that the next generation of telescopes on board the Gamma Ray Observatory will discern several more gamma‐ray pulsars.