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% of the background is rejected; a detection is reported at the 9.0 a level, corresponding to a flux of 1.8 x 10 11 photons cm 2 s 1 above 0.7 TeV (with a factor of 1.5 uncertainty in both flux and energy). Less than 25% 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.
Intense e †ort has gone into the observation of optical, radio, and X-ray gamma-ray burst (GRB) counterparts, either simultaneous to the burst or as quasi-steady lingering remnants. Here we report on a similar study at higher energies of 250 GeV and above using ground-based telescopes. The recent technical advances represented by the atmospheric Cherenkov imaging technique (Cawley & Weekes 1995) have opened up the Ðeld of gamma-ray astronomy above 250 GeV and raised the possibility that these techniques can be used with excellent Ñuence sensitivity in exploring the GRB phenomenon. Observations by the Whipple collaboration of nine BATSE positions, one acquired within 2 minutes of the reported BATSE burst time, using coordinates distributed through the BATSE Coordinates Distribution Network (BACODINE) are reported. No evidence of TeV emission is found, and upper limits to the high-energy delayed or extended emission of observed candidates are calculated. Subject headings : gamma rays : bursts È methods : data analysis
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