  VERITAS is a system of four imaging Cherenkov telescopes located at the Fred
Lawrence Whipple Observatory in southern Arizona. We present here results of
detailed Monte Carlo simulations of the array response to extensive air
showers. Cherenkov image and shower parameter distributions are calculated and
show good agreement with distributions obtained from observations of background
cosmic rays and high-energy gamma-rays. Cosmic-ray and gamma-ray rates are
accurately predicted by the simulations. The energy threshold of the
3-telescope system is about 150 GeV after gamma-hadron separation cuts; the
detection rate after gamma-selection cuts for the Crab Nebula is 7.5
gamma's/min. The three-telescope system is able to detect a source with a flux
equivalent to 10% of the Crab Nebula flux in 1.2 h of observations (5 sigma
detection).
