Very High Energy outburst of Markarian 501 in May 2009
Creators: name: Aliu, E.
name: Archambault, S.
name: Archer, A.
name: Arlen, T.
name: Aune, T.
name: Barnacka, A.
name: Behera, B.
name: Beilicke, M.
name: Benbow, W.
name: Berger, K.
name: Bird, R.
name: Bouvier, A.
name: Böttcher, M.
name: Buchovecky, M.
name: Buckley, J. H.
name: Bugaev, V.
name: Cardenzana, J. V
name: Cerruti, M.
name: Cesarini, A.
name: Chen, X.
name: Ciupik, L.
name: Collins-Hughes, E.
name: Connolly, M. P.
name: Cui, W.
name: Dumm, J.
name: Eisch, J. D.
name: Falcone, A.
name: Federici, S.
name: Feng, Q.
name: Finley, J. P.
name: Fleischhack, H.
name: Fortin, P.
name: Fortson, L.
name: Furniss, A.
name: Galante, N.
name: Gall, D.
name: Gillanders, G. H.
name: Griffin, S.
name: Griffiths, S. T.
name: Grube, J.
name: Gyuk, G.
name: Hütten, M.
name: Håkansson, N.
name: Holder, J.
name: Hughes, G.
name: Humensky, T. B.
name: Johnson, C. A.
name: Kaaret, P.
name: Kar, P.
name: Kelley-Hoskins, N.
name: Kertzman, M.
name: Khassen, Y.
name: Kieda, D.
name: Krause, M.
name: Krawczynski, H.
name: Krennrich, F.
name: Lang, M. J.
name: Madhavan, A. S
name: Maier, G.
name: McArthur, S.
name: McCann, A.
name: Meagher, K.
name: Millis, J.
name: Moriarty, P.
name: Mukherjee, R.
name: Nieto, D.
name: de Bhróithe, A. O'Faoláin
name: Ong, R. A.
name: Orr, M.
name: Otte, A. N.
name: Pandel, D.
name: Park, N.
name: Pelassa, V.
name: Perkins, J. S.
name: Pichel, A.
name: Pohl, M.
name: Popkow, A.
name: Quinn, J.
name: Ragan, K.
name: Reyes, L. C.
name: Reynolds, P. T.
name: Roache, E.
name: Rousselle, J.
name: Rovero, A. C.
name: Saxon, D. B.
name: Sembroski, G. H.
name: Shahinyan, K.
name: Sheidaei, F.
name: Skole, C.
name: Smith, A. W.
name: Staszak, D.
name: Telezhinsky, I.
name: Theiling, M.
name: Todd, N. W.
name: Tucci, J. V.
name: Tyler, J.
name: Varlotta, A.
name: Vassiliev, V. V.
name: Vincent, S.
name: Wakely, S. P.
name: Weiner, O. M.
name: Weinstein, A.
name: Welsing, R.
name: Wilhelm, A.
name: Williams, D. A.
name: Zitzer, B.
name: Baring, M. G.
name: Gónzalez, J. Becerra
name: Cillis, A. N.
name: Horan, D.
name: Paneque, D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The very high energy (VHE; E $&gt;$ 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54938--54956), 2009, as part of an extensive multi-wavelength campaign from radio to VHE. Strong VHE $γ$-ray activity was detected on May 1st with Whipple and VERITAS, when the flux (E $&gt;$ 400 GeV) increased to 10 times the pre-flare baseline flux ($3.9{\times 10^{-11}}~{\rm ph~cm^{-2}~s^{-1}}$), reaching five times the flux of the Crab Nebula. This coincided with a decrease in the optical polarization and a rotation of the polarization angle by 15$^{\circ}$. This VHE flare showed a fast flux variation with an increase of a factor $\sim$4 in 25 minutes, and a falling time of $\sim$50 minutes. We present the observations of the quiescent state previous to the flare and of the high state after the flare, focusing on the flux and spectral variability from Whipple, VERITAS, Fermi-LAT, RXTE, and Swift combined with optical and radio data.
description: 13 pages, 10 figures. Accepted for publication in Astronomy and Astrophysics