The CAT Imaging Telescope for Very-High-Energy Gamma-Ray Astronomy

Abstract

The CAT (Cherenkov Array at Th'emis) imaging telescope, equipped with a veryhigh -definition camera (546 fast phototubes with 0:12 ffi spacing surrounded by 54 Preprint submitted to Elsevier Preprint 31 March larger tubes in two guard rings) started operation in Autumn 1996 on the site of the former solar plant Th'emis (France). Using the atmospheric Cherenkov technique, it detects and identifies very high energy fl-rays in the range 250 GeV to a few tens of TeV. The instrument, which has detected three sources (Crab nebula, Markarian 421 and Markarian 501), is described in detail. Key words: Gamma-Ray Astronomy, Atmospheric Cherenkov detector 1 Introduction The recent development of Very-High-Energy Gamma-Ray Astronomy is essentially due to Atmospheric Cherenkov Telescopes (ACT). Since 1988, two arrays of Cherenkov detectors, ASGAT [1] and THEMISTOCLE [2] have been operated on the site of the former solar plant "Th'emis", close to Font-Romeu in the French Pyrenees. They consist of..