Observation of VHE gamma-ray emission from the Active Galactic Nucleus 1ES1959+650 using the MAGIC telecope

Abstract

The MAGIC Cherenkov telescope has observed very high energy (VHE) gamma-ray emission from the Active Galactic Nucleus 1ES1959+650 during six hours in September and October 2004. The observations were carried out alternated with the Crab Nebula, whose data were used as reference source for optimizing gamma/hadron separation and for flux comparison. The data analysis shows VHE gamma-ray emission of 1ES1959+650 with ~ 8 sigma significance, at a time of low activity in both optical and X-ray wavelengths. An integral flux above ~ 180 GeV of about 20% of the Crab was obtained. The light curve, sampled over 7 days, shows no significant variations. The differential energy spectrum between 180 GeV and 2 TeV can be fitted with a power law of index -2.72 +/- 0.14. The spectrum is consistent with the slightly steeper spectrum seen by HEGRA at higher energies, also during periods of low X-ray activity.