ATMOSPHERIC ATTENUATION IN GAMMA-RAY ASTRONOMY

Ground-based gamma astronomy is based on the detection of the Cherenko v photons. Aerosols and high altitude clouds enhance photon scattering and then disturb the ground detection of Cherenkov showers. We presen t Monte Carlo simulations for the propagation of gamma and proton show ers (energy in the range 50 GeV-2 TeV) in inhomogeneous atmosphere wit h aerosols and clouds of weak optical depth, The results indicate clea rly that atmospheric scattering reduces significantly the Cherenkov si gnal for low-energy showers (50-500 GeV for gamma induced showers). A phenomenological relation is proposed for the estimation of the ground atmospheric attenuation of the Cherenkov signal. (C) 1998 Elsevier Sc ience B.V.