  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 > 10, and an
electron population with spectral index < 2.3.
