Discovery of Very High Energy Gamma Rays from 1ES 1218+30.4

Albert, J.; Aliu, E.; Anderhub, H.; Antoranz, P.; Armada, A.; Asensio, M.; Baixeras, C.; Barrio, J. A.; Bartelt, M.; Bartko, H.; Bastieri, Denis; Bavikadi, S. R.; 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.; Curtef, V.; Danielyan, V.; Dazzi, Francesco; DE ANGELIS, A.; DE LOS REYES, R.; DE LOTTO, B.; DOMINGO SANTAMARA, E.; Dorner, D.; Doro, Michele; Errando, M.; Fagiolini, M.; Ferenc, D.; Fernndez, E.; Firpo, R.; Flix, J.; Fonseca, M. V.; Font, L.; Galante, N.; Garczarczyk, M.; Gaug, M.; Giller, M.; Goebel, F.; Hakobyan, D.; Hayashida, M.; Hengstebeck, T.; Hhne, D.; Hose, J.; Jacon, P.; Kalekin, O.; Kranich, D.; Laille, A.; Lenisa, T.; Liebing, P.; Lindfors, E.; Longo, F.; Lpez, J.; Lpez, M.; Lorenz, E.; Lucarelli, F.; Majumdar, P.; Maneva, G.; Mannheim, K.; Mariotti, Mose'; Martnez, M.; Mase, K.; Mazin, D.; Meucci, M.; Meyer, M.; Miranda, J. M.; Mirzoyan, R.; Mizobuchi, S.; Moralejo, A.; Nilsson, K.; OA WILHELMI, E.; Ordua, R.; Otte, N.; Oya, I.; Paneque, D.; Paoletti, R.; Pasanen, M.; Pascoli, Donatella; Pauss, F.; Pavel, N.; Pegna, R.; Persic, M.; Peruzzo, Luigi; Piccioli, A.; Poller, M.; Prandini, Elisa; Rhode, W.; Rico, J.; Riegel, B.; Rissi, M.; Robert, A.; Rgamer, S.; Saggion, Antonio; Snchez, A.; Sartori, Paolo; Scalzotto, VILLI MARIO; Schmitt, R.; Schweizer, T.; Shayduk, M.; Shinozaki, K.; Shore, S. N.; Sidro, N.; Sillanp, A.; SOBCZY SKA, D.; Stamerra, A.; Stark, L. S.; Takalo, L.; Temnikov, P.; Tescaro, D.; Teshima, M.; Tonello, N.; Torres, A.; Torres, D. F.; Turini, N.; Vankov, H.; Vardanyan, A.; Vitale, V.; Wagner, R. M.; Wibig, T.; Wittek, W.; Zapatero, AND J.

doi:10.1086/504845

The MAGIC collaboration has studied the high-frequency-peaked BL Lac object 1ES 1218 + 30.4, at a redshift z = 0.182, using the MAGIC imaging air Cerenkov telescope located on the Canary Island of La Palma. A gamma-ray signal was observed with 6.4 sigma significance. The differential energy spectrum for an energy threshold of 120 GeV can be fitted by a simple power law, yielding F-E = (8.1 +/- 2.1) x 10(-7)[E/(250 GeV)](-3.0 +/- 0.4) TeV-1 F (E) m(-2) s(-1). During the 6 days of observation in 2005 January, no time variability on timescales of days was found within the statistical errors. The observed integral flux above 350 GeV is nearly a factor of 2 below the upper limit reported by the Whipple collaboration in 2003.