B2 1215+30 is a BL Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes , and subsequently confirmed by the VERITAS observatory with data collected between 2009 and 2012 .
In 2014 February 08 , VERITAS detected a large-amplitude flare from B2 1215+30 during routine monitoring observations of the blazar 1ES 1218+304 , located in the same field of view .
The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of < 3.6 h. Multiwavelength observations with Fermi -LAT , Swift , and the Tuorla observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare , with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity .
When interpreted in the framework of a one-zone leptonic model , the observed emission implies a high degree of beaming , with Doppler factor \delta > 10 , and an electron population with spectral index p < 2.3 .