A high resolution imaging detector for TeV gamma-ray astronomy

Details are presented of an atmospheric Cherenkov telescope for use in very high energy gamma-ray astronomy which consists of a cluster of 109 close-packed photomultiplier tubes at the focus of a 10 meter optical reflector. The images of the Cherenkov flashes generated both by gamma-ray and charged cosmic-ray events are digitized and recorded. Subsequent off-line analysis of the images improves the significance of the signal to noise ratio by a factor of 10 compared with non-imaging techniques

Observation of TeV Gamma-rays from the Crab Nebula using the Atmospheric Cherenkov Imaging Technique

The Whipple Observatory 10-m reflector, operating as a 37-pixel camera, has been used to observe the Crab Nebula in TeV gamma rays. By selecting gamma-ray images based on their predicted properties, more than 98 percent of the background is rejected; a detection is reported at the 9.0-sigma level, corresponding to a flux of 1.8 x 10 to the -11th photons sq cm/s above 0.7 TeV (with a factor of 1.5 uncertainty in both flux and energy). Less than 25 percent of the observed flux is pulsed at the period of PSR 0531. There is no evidence for variability on time scales from months to years. Although continuum emission from the pulsar cannot be ruled out, it seems more likely that the observed flux comes from the hard Compton synchrotron spectrum of the nebula

Search for TeV gamma rays from the X-ray pulsar 1E2259+586

Evidence for TeV gamma-ray emission from 1E2259 + 586 has recently been reported by the Durham Group (Brazier et al., 1990). Evidence suggests that the source is a steady gamma-ray emitter, with a flux an order of magnitude higher than that of the Crab Nebula (Weekes et al., 1989). The Whipple Collaboration observed 1E2259 + 586 for a total of 80 H between November 1985 and November 1988 using the atmospheric Cherenkov imaging technique. These observations, were analysed for evidence of periodic emission at the fundamental and second harmonic of the X-ray period. No evidence for gamma-ray emission from this source is found