Observations of 1ES1959+650 with the HEGRA System of Imaging Air Cherenkov Telescopes

摘要

The nearby BL Lac object 1ES1959+650 (z = 0.047) has been observed with the HEGRA system of imaging air Cherenkov telescopes.Based upon a data-set of 94 hrs taken from July 2000 until October 2001,a weak detection (5.4 sigma) has been obtained corresponding to a flux level of 8 % of the Crab flux above an energy threshold of 2 TeV for the observations at zenith angles between 37deg and 45deg.During recent observations from May until July 2002,the source has been observed to undergo strong outbursts at TeV and X-ray energies.The energy spectrum during the flares is hard and exhibits curvature,whereas during the low-state a power-law with a photon-index of 3.3+-0.7 describes well the data.