Discovery of Very High Energy Gamma Rays from 1ES 1218+ 30.4
Journal
The Astrophysical Journal Letters 642, L119, 2006
ticlealbert2006discovery, title=Discovery of Very High Energy Gamma Rays from 1ES 1218+ 30.4, author=Albert, J and Aliu, E and Anderhub, H and Antoranz, P and Armada, A and Asensio, M and Baixeras, C and Barrio, JA and Bartelt, M and Bartko, H and others,
Abstract:
The MAGIC collaboration has studied the high peaked BL-Lac object 1ES1218+30.4 at a redshift z = 0.182, using the MAGIC imaging air Cherenkov telescope located on the Canary island of La Palma. A gamma-ray signal was observed with 6.4sigma significance. The differential energy spectrum for an energy threshold of 120GeV can be fitted by a simple power law yielding F_E(E) = (8.1+-2.1)*10^-7 (E/250GeV)^(-3.0+-0.4) TeV^-1 m^-2 s^-1. During the six days of observation in January 2005 no time variability on time scales of days was found within the statistical errors. The observed integral flux above 350GeV is nearly a factor two below the the upper limit reported by the Whipple Collaboration in 2003.