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

Abstract

Aims. We searched for very high energy (VHE) γ-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 5.2σ and a photon flux above 1 TeV of (7.3 ±0.7stat ± 2.2sys) × 10-13 cm-2s-1. The photon spectrum is compatible with a power law dN/dE ∝ E-Γ with a photon index Γ = 2.3 ± 0.2stat ±0.2sys. The source is point-like within the angular resolution of the telescope. © ESO 2007.