Observation of Very High Energy Gamma‐Ray Emission from the Active Galactic Nucleus 1ES 1959+650 Using the MAGIC Telescope

Albert, J.; Aliu, E.; Anderhub, H.; Antoranz, P.; Armada, A.; Asensio, M.; Baixeras, C.; Barrio, J. A.; Bartko, H.; Bastieri, Denis; Bednarek, W.; Berger, K.; Bigongiari, C.; Biland, A.; Bisesi, E.; Bock, R. K.; Bretz, T.; Britvitch, I.; Camara, M.; Chilingarian, A.; Ciprini, S.; Coarasa, J. A.; Commichau, S.; Contreras, J. L.; Cortina, J.; Danielyan, V.; Dazzi, Francesco; De Angelis, A.; de los Reyes, R.; De Lotto, B.; Domingo‐santamaria, E.; Dorner, D.; Doro, Michele; Errando, M.; Ferenc, D.; Fernandez, E.; Firpo, R.; Flix, J.; Fonseca, M. V.; Font, L.; Galante, N.; Garczarczyk, M.; Gaug, M.; Gebauer, J.; Giannitrapani, R.; Giller, M.; Goebel, F.; Hakobyan, D.; Hayashida, M.; Hengstebeck, T.; Hohne, D.; Hose, J.; Jacon, P.; Kalekin, O.; Kranich, D.; Laille, A.; Lenisa, T.; Liebing, P.; Lindfors, E.; Longo, F.; Lopez, J.; Lopez, M.; Lorenz, E.; Lucarelli, F.; Majumdar, P.; Maneva, G.; Mannheim, K.; Mariotti, Mose'; Martinez, M.; Mase, K.; Mazin, D.; Merck, C.; Merck, M.; Meucci, M.; Meyer, M.; Miranda, J. M.; Mirzoyan, R.; Mizobuchi, S.; Moralejo, A.; Nilsson, K.; Ona‐wilhelmi, E.; Orduna, R.; Otte, N.; Oya, I.; Paneque, D.; Paoletti, R.; Pasanen, M.; Pascoli, Donatella; Pauss, F.; Pavel, N.; Pegna, R.; Peruzzo, Luigi; Piccioli, A.; Pin, M.; Prandini, Elisa; Rico, J.; Rhode, W.; Riegel, B.; Rissi, M.; Robert, A.; Rossato, G.; Rugamer, S.; Saggion, A.; Sanchez, A.; Sartori, Paolo; Scalzotto, VILLI MARIO; Schmitt, R.; Schweizer, T.; Shayduk, M.; Shinozaki, K.; Sidro, N.; Sillanpaa, A.; Sobczynska, D.; Stamerra, A.; Stark, L.; Takalo, L.; Temnikov, P.; Tescaro, D.; Teshima, M.; Tonello, N.; Torres, A.; Torres, D. F.; Turini, N.; Vankov, H.; Vitale, V.; Wagner, R. M.; Wibig, T.; Wittek, W.; Zapatero, J.

doi:10.1086/499421

The MAGIC Cerenkov telescope has observed very high energy (VHE) gamma-ray emission from the active galactic nucleus 1ES 1959+650 during 6 hr in 2004 September and October. The observations were carried out alternating with observations of the Crab Nebula, whose data were used as a reference source for optimizing gamma -ray/hadron separation and for flux comparison. The data analysis shows VHE gamma-ray emission of 1ES 1959+650 with similar to 8 sigma significance, at a time of low activity in both optical and X-ray wavelengths. An integral flux above similar to 180 GeV of about 20% that of the Crab Nebula 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.