Aleksić, J.Ansoldi, S.Antonelli, L.Antoranz, P.Babic, A.Bangale, P.Barrio, J.Becerra González, J.Bednarek, W.Bernardini, E.Biasuzzi, B.Biland, A.Blanch, O.Bonnefoy, S.Bonnoli, G.Borracci, F.Bretz, T.Carmona, E.Carosi, A.Colin, P.et al.2018-06-192018-06-192015Monthly Notices of the Royal Astronomical Society, 2015; 451(1):739-7500035-87111365-2966http://hdl.handle.net/2440/112966The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in very high energy (VHE) γ-rays in 2008. Until now, the broad-band spectrum of 1ES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwavelength observations from γ-rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of 1ES 0806+524 to date. The stereoscopic Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) observations yielded a γ-ray signal above 250 GeV of (3.7 ± 0.7) per cent of the Crab Nebula flux with a statistical significance of 9.9σ. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE γ-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in 1ES 0806+524. The spectrum of this flare is well described by a power law with a photon index of 2.97 ± 0.29 between ∼150 GeV and 1 TeV and an integral flux of (9.3 ± 1.9) per cent of the Crab nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. The broad-band spectral energy distribution can be described with a one-zone synchrotron self-Compton model with parameters typical for HBLs, indicating that 1ES 0806+524 is not substantially different from the HBLs previously detected.en© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.Radiation mechanisms: non-thermal, galaxies: active, BL Lacertae objects: individual: 1ES 0806+524, galaxies: jets, gamma rays: galaxiesJournal article003007792710.1093/mnras/stv8950003608278000572-s2.0-84938225881387874Einecke, S. [0000-0001-9687-8237]