THE SYSTEM OF IMAGING ATMOSPHERIC CHERENKOV TELESCOPES: THE NEW PROSPECTS FOR VHE GAMMA RAY ASTRONOMY. F.A. Aharonian, A.A. Chilingarian, R.G. Mirzoyan Yerevan Physics Institute, Alikhanian Brothers 2, Yerevan, 375036, Armenia. A.K. Konopelko, A-V. Plyasheshnikov Altai State University, Dimitrov 66, Barnaul, 656099, Russia (Received 7 April 1992; accepted 15 October 1992) Using Monte Carlo simulations the possibilities are investigated for registration of VHE gamma radiation by means of systems of imaging air Cherenkov telescopes (TACT). It is shown that even a system of IACT’s with moderate properties (three telescopes with the geometrical area of the optical reflector =5 m2 and the angular size of the pixel ~0.41’) could provide the energy resolution 20-25x and achieve the sensitivity (minimum detectable flux) up to 10-‘2photon/cm 2s at the effective energy threshold =l TeV. 1. Introduction. So far all observations of primary gamma rays at E= 1 TeV have been made with Air Cherenkov Telescopes (ACT). In the foreseeable future this technique will dominate at least at energies Es10 TeV. One of the most remarkable features of the ACT’s is their high rate capability. For collection area Sefp3*108cm2 , easily achieved by simple ACT, the counting rate of VHE gamma rays from the Crab Nebula should be higher than 0.1 events per minute. However, this important feature can acquire its practical significance only in the case of effective suppression of the background induced by the proton-nuclear component of the primary cosmic radiation. Different ways for cosmic ray background rejection were proposed (for review see, e.g., Weekes, 1988); however at present only the so called imaging technique is realized as a powerful method for significant improvement of the sensitivity of detectors in VHE gamma ray astronomy. The application of the multichannel Cherenkov light receiver in the focus of the high quality optical reflector gives a possibility to separate gamma ray- and proton-induced showers, analyzing the Experimental Astronomy 2: 331-344, 1993. 0 1993 Kluwer Academic Publishers. Printed in the Netherlands.