Discovery of a very high energy gamma-ray signal from the 3C 66A/B region

Abstract

The MAGIC telescope observed the region around the distant blazar 3C 66A for 54.2 hr in 2007 August-December. The observations resulted in the discovery of a γ-ray source centered at celestial coordinates R.A. = 2h23m12s and decl. = 43°0farcm7 (MAGIC J0223+430), coinciding with the nearby radio galaxy 3C 66B. A possible association of the excess with the blazar 3C 66A is discussed. The energy spectrum of MAGIC J0223+430 follows a power law with a normalization of (1.7 ± 0.3stat ± 0.6syst) × 10-11 TeV-1 cm-2 s-1 at 300 GeV and a photon index Γ = -3.10 ± 0.31stat ± 0.2syst.