RT Journal Article T1 Discovery of a very high energy gamma-ray signal from the 3C 66A/B region A1 Antoranz Canales, Pedro A1 Barrio Uña, Juan Abel A1 Contreras González, José Luis A1 Fonseca González, María Victoria A1 Miranda Pantoja, José Miguel A1 Nieto Castaño, Daniel AB 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 gamma-ray source centered at celestial coordinates R.A. = 2(h)23(m)12(s) and decl.=43 degrees 0'.7 (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 +/- 0.3(stat) +/- 0.6(syst)) x 10(-11) TeV(-1) cm(-2) s(-1) at 300 GeV and a photon index Gamma = -3.10 +/- 0.31(stat) +/- 0.2(syst). PB IOP Publishing SN 2041-8205 YR 2009 FD 2009-02-10 LK https://hdl.handle.net/20.500.14352/43999 UL https://hdl.handle.net/20.500.14352/43999 LA eng NO © The American Astronomical Society. We thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, and Spanish MCINN is gratefully acknowledged. This work was also supported by ETH Research Grant TH 34/043, by the Polish MNiSzW Grant N N203 390834, and by the YIP of the Helmholtz Gemeinschaft. NO German BMBF NO German MPG NO Italian INFN NO Spanish MCINN NO ETH NO Polish MNiSzW NO YIP of the Helmholtz Gemeinschaft DS Docta Complutense RD 8 abr 2025