OBSERVATION OF THE CRAB-NEBULA WITH AN ULTRAVIOLET CHERENKOV CAMERA

Gamma-ray astronomy at energies of a few hundred GeV is now well estab lished, with the observation of emission from the Crab Nebula by at le ast five independent groups. The technique is based on the detection o f the Cherenkov light emitted by gamma-ray induced air showers. It req uires clear, moonless nights, which seriously curtail the useful duty cycle. It is shown here that by detecting the UV Cherenkov photons ins tead of the full visible Cherenkov spectrum, the observations can be e xtended to moonlit nights, with lower constraints on the background li ght from the moon and stars, but with a somewhat higher energy thresho ld.