%0 Electronic Article
%A Aliu, E.
%A Archer, A.
%A Aune, T.
%A Barnacka, A.
%A Behera, B.
%A Beilicke, M.
%A Benbow, W.
%A Berger, K.
%A Bird, R.
%A Buckley, J. H.
%A Bugaev, V.
%A Byrum, K.
%A Cardenzana, J. V
%A Cerruti, M.
%A Chen, Xuhui
%A Ciupik, L.
%A Connolly, M. P.
%A Cui, W.
%A Dickinson, H. J.
%A Dumm, J.
%A Eisch, J. D.
%A Errando, M.
%A Falcone, A.
%A Federici, S.
%A Feng, Q.
%A Finley, J. P.
%A Fortin, P.
%A Fortson, L.
%A Furniss, A.
%A Galante, N.
%A Gillanders, G. H.
%A Griffin, S.
%A Griffiths, S. T.
%A Grube, J.
%A Gyuk, G.
%A Håkansson, N.
%A Hanna, D.
%A Holder, J.
%A Hughes, Gareth
%A Humensky, T. B.
%A Johnson, C. A.
%A Kaaret, P.
%A Kertzman, P. Kar M.
%A Khassen, Y.
%A Kieda, D.
%A Krawczynski, H.
%A Krennrich, F.
%A Kumar, S.
%A Lang, M. J.
%A Madhavan, A.
%A McArthur, S.
%A McCann, A.
%A Meagher, K.
%A Millis, J.
%A Moriarty, P.
%A Nieto, D.
%A de Bhróithe, A. O'Faoláin
%A Ong, R. A.
%A Orr, M.
%A Otte, A. N.
%A Park, N.
%A Perkins, J. S.
%A Pohl, Martin
%A Popkow, A.
%A Prokoph, H.
%A Pueschel, E.
%A Quinn, J.
%A Ragan, K.
%A Rajotte, J.
%A Reyes, L. C.
%A Reynolds, P. T.
%A Richards, G. T.
%A Roache, E.
%A Sembroski, G. H.
%A Shahinyan, K.
%A Staszak, D.
%A Telezhinsky, I.
%A Tucci, J. V.
%A Tyler, J.
%A Varlotta, A.
%A Vassiliev, V. V.
%A Wakely, S. P.
%A Weinstein, A.
%A Welsing, R.
%A Wilhelm, A.
%A Williams, D. A.
%A Zitzer, B.
%T VERITAS Observations of the BL Lac Object PG 1553+113
%N arXiv:1411.1439
%M PUBDB-2014-04306
%M arXiv:1411.1439
%D 2014
%Z OA
%X We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560 GeV, is well described by a power law with a spectral index of 4.33 ±0.09. The time-averaged integral flux above 200 GeV measured for this period was (1.69 ±0.06) ×10<sup>−11</sup>  ph  cm<sup>−2</sup>  s<sup>−1</sup>, corresponding to 6.9% of the Crab Nebula flux. We also present the combined γ-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100 MeV to 560 GeV. The data are well fit by a power law with an exponential cutoff at 101.9 ±3.2  GeV . The origin of the cutoff could be intrinsic to PG 1553+113 or be due to the γ-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of z \negthinspace  >  \negthinspace 0.395 based on optical/UV observations of PG 1553+113, the cutoff would be dominated by EBL absorption. Conversely, the small statistical uncertainties of the VERITAS energy spectrum have allowed us to provide a robust upper limit on the redshift of PG 1553+113 of z \negthinspace  ≤ \negthinspace 0.62. A strongly-elevated mean flux of (2.50 ±0.14) ×10<sup>−11</sup>  ph  cm<sup>−2</sup>  s<sup>−1</sup> (10.3% of the Crab Nebula flux) was observed during 2012, with the daily flux reaching as high as (4.44 ±0.71) ×10<sup>−11</sup>  ph  cm<sup>−2</sup>  s<sup>−1</sup> (18.3% of the Crab Nebula flux) on MJD 56048. The light curve measured during the 2012 observing season is marginally inconsistent with a steady flux, giving a χ<sup>2</sup> probability for a steady flux of 0.03%.
%F PUB:(DE-HGF)25 ; PUB:(DE-HGF)15
%9 PreprintInternal Report
%U https://bib-pubdb1.desy.de/record/192777