High Energy γ-rays from the Direction of the Crab Pulsar

Observation of TeV gamma rays from the Crab nebula using the atmospheric Cerenkov imaging technique

“…Several detections were reported at very high energies (Grindlay 1972;Jennings et al 1974;Grindlay, Helmken, and Weekes 1976;Porter et al 1976;Erickson, Fickle, and Lamb 1976;Vishwanath 1982;Vishwanath et al 1985;Gupta et al 1977;Gibson et al 1982h;Dowthwaite et al 1984;Turner et al 1985;Bhat et al 1986), but the statistical significance was not high, and upper limits were also presented which appeared to be in conflict with the reported fluxes (Helmken et al 1973;Vishwanath et al 1986;Bhat et al 1987). At energies above 1 TeV there were also reports of emission from the direction of the Crab (Mukanov 1983;Boone et al 1984;Dzikowski et al 1981;Kirov et al 1985), but, because of the limited angular resolution and the absence of accurate timekeeping, it was not possible to identify the source of the observed signal with the nebula or the pulsar. Again there may be conflicting upper limits (Craig et al 1981 ;Watson 1985).…”