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MAGIC detection of an unprecedented activity from S50716+714 at very-high-energy gamma rays

The MAGIC telescopes have observed a strong increase in the very-high-energy (VHE ; >100 GeV) gamma-ray flux from S50716+714 (RA: 7:21:53.45, Dec: 71:20:36.36, J2000.0). MAGIC observed the source for ~2 hours on 2017/12/28. The preliminary analysis of the MAGIC data indicates increasing flux reaching up to 1.5 times the flux of the Crab nebula above 150 GeV, which is ~6 times higher than the VHE flux from this source during the 2015 flare (ATel #6999). S50716+714 is an intermediate Synchrotron peaked blazar (IBL, Giommi et al. 1999, A&A, 351, 59 ; Ackermann et al. 2011, ApJ, 743, 171) located at the redshift of ~0.3 (Nilsson et al., 2008, A&A, 487, L29 ; Danforth et al., 2013, ApJ, 764, 57). VHE gamma-ray emission from S50716+714 was first reported by the MAGIC collaboration during high optical state of the source (Anderhub et al. 2009, ApJ, 704, L129). Observations of MAGIC were triggered by the hard spectrum of the source (spectral index = -1.86 +/- 0.14, Flux (100MeV-300 GeV) = 0.58 +/- 0.12 e-06 ph cm^-2.) found in the Fermi-LAT data in the 24 hour period started on 2017-12-25 at 18:00:00 UTC. MAGIC observations on S50716+714 will continue during the next two nights and possibly after the moon break and multi-wavelength observations are encouraged. The MAGIC contact person for these observations is R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located on the Canary island of La Palma, Spain, and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 50 TeV.

GeV ; TeV ; VHE ; AGN ; Blazar

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