Observation of VHE γ-rays from Cassiopeia A with the MAGIC telescope

Aims. We searched for very high energy (VHE)gamma-ray emission from the supernova remnant Cassiopeia A Methods. The shell-type supernova remnant Cassiopeia A was observed with the 17 m MAGIC telescope between July 2006 and January 2007 for a total time of 47 h. Results. The source was detected above an energy of 250 GeV with a significance of 5.2s and a photon flux above 1 TeV of (7.3 +/- 0.7(stat) +/- 2.2(sys)) x 10(-13) cm(-2)s(-1). The photon spectrum is compatible with a power law dN/dE proportional to E-r with a photon index Gamma = 2.3 +/- 0.2(stat) +/- 0.2(sys). The source is point- like within the angular resolution of the telescope.