A HYBRID VERSION OF THE WHIPPLE OBSERVATORYS AIR CHERENKOV IMAGING CAMERA FOR USE IN MOONLIGHT

A hybrid version of the Whipple Observatory's atmospheric Cherenkov im aging camera that permits observation during periods of bright moonlig ht is described. The hybrid camera combines a blue-light blocking filt er with the standard Whipple imaging camera to reduce sensitivity to w avelengths greater than 360 nm, Data taken with this camera are found to be foe from the effects of the moonlit night-sky after the applicat ion of simple off-line noise filtering. This camera has been used to s uccessfully detect TeV gamma rays, in bright moon light, from both the Crab Nebula and the active galactic nucleus Markarian 421 at the 4.9 sigma and 3.9 sigma levels of statistical significance, respectively, The energy threshold of the camera is estimated to be 1.1 (+0.6/-0.3) TeV from Monte Carlo simulations.