Submitted to Astrophysical Journal Supplements Fermi Large Area Telescope Third Source Catalog F. Acero1, M. Ackermann2, M. Ajello3, A. Albert4, W. B. Atwood5, M. Axelsson6,7,8, L. Baldini9, J. Ballet1,10, G. Barbiellini11,12, D. Bastieri13,14, A. Belfiore5,15,16, R. Bellazzini9, E. Bissaldi17, R. D. Blandford4, E. D. Bloom4, J. R. Bogart4, R. Bonino18,19, E. Bottacini4, J. Bregeon20, R. J. Britto21, P. Bruel22, R. Buehler2, T. H. Burnett23,24, S. Buson13,14, G. A. Caliandro4,25, R. A. Cameron4, R. Caputo5, M. Caragiulo26, P. A. Caraveo16, J. M. Casandjian1, E. Cavazzuti27,28, E. Charles4, R.C.G. Chaves20, A. Chekhtman29, C. C. Cheung30, J. Chiang4, G. Chiaro14, S. Ciprini27,31, R. Claus4, J. Cohen-Tanugi20, L. R. Cominsky32, J. Conrad6,8,33,34, S. Cutini27,31, F. D’Ammando35,36, A. de Angelis37, M. DeKlotz38, F. de Palma26,39, R. Desiante11,40, S. W. Digel4,41, L. Di Venere42, P. S. Drell4, R. Dubois4, D. Dumora43, C. Favuzzi42,26, S. J. Fegan22, E. C. Ferrara44, J. Finke30, A. Franckowiak4, Y. Fukazawa45, S. Funk4, P. Fusco42,26, F. Gargano26, D. Gasparrini27,31, B. Giebels22, N. Giglietto42,26, P. Giommi27, F. Giordano42,26, M. Giroletti35, T. Glanzman4, G. Godfrey4, I. A. Grenier1, M.-H. Grondin43, J. E. Grove30, L. Guillemot46, S. Guiriec44,47, D. Hadasch48, A. K. Harding44, E. Hays44, J.W. Hewitt49,50, A. B. Hill51,4,52, D. Horan22, G. Iafrate11,53, T. Jogler4, G. J´ohannesson54, R. P. Johnson5, A. S. Johnson4, T. J. Johnson29, W. N. Johnson30, T. Kamae4, J. Kataoka55, J. Katsuta45, M. Kuss9, G. La Mura14,48, D. Landriu1, S. Larsson6,8,7, L. Latronico18, M. Lemoine-Goumard43,56, J. Li57, L. Li58,8, F. Longo11,12, F. Loparco42,26, B. Lott43, M. N. Lovellette30, P. Lubrano59,60, G. M. Madejski4, F. Massaro61, M. Mayer2, M. N. Mazziotta26, J. E. McEnery44,62, P. F. Michelson4, N. Mirabal44,47, T. Mizuno63, A. A. Moiseev50,62, M. Mongelli26, M. E. Monzani4, A. Morselli64, I. V. Moskalenko4, S. Murgia65, E. Nuss20, M. Ohno45, T. Ohsugi63, N. Omodei4, M. Orienti35, E. Orlando4, J. F. Ormes66, D. Paneque67,4, J. H. Panetta4, J. S. Perkins44, M. Pesce-Rollins9, F. Piron20, G. Pivato9, T. A. Porter4, J. L. Racusin44, R. Rando13,14, M. Razzano9,68, S. Razzaque21, A. Reimer48,4, O. Reimer48,4, T. Reposeur43, L. S. Rochester4, R. W. Romani4, D. Salvetti16, M. S´anchez-Conde8,6, P. M. Saz Parkinson5,69, A. Schulz2, C. Sgr`o9, E. J. Siskind70, D. A. Smith43, F. Spada9, G. Spandre9, P. Spinelli42,26, T. E. Stephens71, A. W. Strong72, D. J. Suson73, H. Takahashi45, T. Takahashi74, Y. Tanaka63, J. G. Thayer4, J. B. Thayer4, D. J. Thompson44, L. Tibaldo4, O. Tibolla75, D. F. Torres57,76, E. Torresi77, E. Troja44,62, B. Van Klaveren4, G. Vianello4, B. L. Winer78, K. S. Wood30, M. Wood4, S. Zimmer6,8 –2– 1Laboratoire AIM, CEA-IRFU/CNRS/Universit´eParis Diderot, Service d’Astrophysique, CEA Saclay, 91191 Gif sur Yvette, France 2Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen, Germany 3Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634- 0978, USA 4W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmol- ogy, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA 5Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064, USA 6Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden 7Department of Astronomy, Stockholm University, SE-106 91 Stockholm, Sweden 8The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, SE-106 91 Stockholm, Sweden 9Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, Italy 10email: [email protected] 11Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste, Italy 12Dipartimento di Fisica, Universit`adi Trieste, I-34127 Trieste, Italy 13Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova, Italy 14Dipartimento di Fisica e Astronomia “G. Galilei”, Universit`adi Padova, I-35131 Padova, Italy 15Universit`adegli Studi di Pavia, 27100 Pavia, Italy 16INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano, Italy 17Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, and Universit`adi Trieste, I-34127 Trieste, Italy 18Istituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino, Italy 19Dipartimento di Fisica Generale “Amadeo Avogadro” , Universit`adegli Studi di Torino, I-10125 Torino, Italy 20Laboratoire Univers et Particules de Montpellier, Universit´eMontpellier 2, CNRS/IN2P3, Montpellier, France 21Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa 22Laboratoire Leprince-Ringuet, Ecole´ polytechnique, CNRS/IN2P3, Palaiseau, France 23Department of Physics, University of Washington, Seattle, WA 98195-1560, USA 24email: [email protected] 25Consorzio Interuniversitario per la Fisica Spaziale (CIFS), I-10133 Torino, Italy –3– 26Istituto Nazionale di Fisica Nucleare, Sezione di Bari, 70126 Bari, Italy 27Agenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma, Italy 28email: [email protected] 29College of Science, George Mason University, Fairfax, VA 22030, resident at Naval Research Laboratory, Washington, DC 20375, USA 30Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352, USA 31INAF Osservatorio Astronomico di Roma, I-00040 Monte Porzio Catone (Roma), Italy 32Department of Physics and Astronomy, Sonoma State University, Rohnert Park, CA 94928-3609, USA 33Royal Swedish Academy of Sciences Research Fellow, funded by a grant from the K. A. Wallenberg Foundation 34The Royal Swedish Academy of Sciences, Box 50005, SE-104 05 Stockholm, Sweden 35INAF Istituto di Radioastronomia, 40129 Bologna, Italy 36Dipartimento di Astronomia, Universit`adi Bologna, I-40127 Bologna, Italy 37Dipartimento di Fisica, Universit`adi Udine and Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Gruppo Collegato di Udine, I-33100 Udine 38Stellar Solutions Inc., 250 Cambridge Avenue, Suite 204, Palo Alto, CA 94306, USA 39Universit`aTelematica Pegaso, Piazza Trieste e Trento, 48, 80132 Napoli, Italy 40Universit`adi Udine, I-33100 Udine, Italy 41email: [email protected] 42Dipartimento di Fisica “M. Merlin” dell’Universit`ae del Politecnico di Bari, I-70126 Bari, Italy 43Centre d’Etudes´ Nucl´eaires de Bordeaux Gradignan, IN2P3/CNRS, Universit´eBordeaux 1, BP120, F- 33175 Gradignan Cedex, France 44NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 45Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan 46Laboratoire de Physique et Chimie de l’Environnement et de l’Espace – Universit´ed’Orl´eans / CNRS, F-45071 Orl´eans Cedex 02, France and Station de radioastronomie de Nan¸cay, Observatoire de Paris, CNRS/INSU, F-18330 Nan¸cay, France 47NASA Postdoctoral Program Fellow, USA 48Institut f¨ur Astro- und Teilchenphysik and Institut f¨ur Theoretische Physik, Leopold-Franzens- Universit¨at Innsbruck, A-6020 Innsbruck, Austria 49Department of Physics and Center for Space Sciences and Technology, University of Maryland Baltimore County, Baltimore, MD 21250, USA 50Center for Research and Exploration in Space Science and Technology (CRESST) and NASA Goddard –4– Space Flight Center, Greenbelt, MD 20771, USA 51School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, UK 52Funded by a Marie Curie IOF, FP7/2007-2013 - Grant agreement no. 275861 53Osservatorio Astronomico di Trieste, Istituto Nazionale di Astrofisica, I-34143 Trieste, Italy 54Science Institute, University of Iceland, IS-107 Reykjavik, Iceland 55Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169- 8555, Japan 56Funded by contract ERC-StG-259391 from the European Community 57Institute of Space Sciences (IEEC-CSIC), Campus UAB, E-08193 Barcelona, Spain 58Department of Physics, KTH Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm, Sweden 59Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia, Italy 60Dipartimento di Fisica, Universit`adegli Studi di Perugia, I-06123 Perugia, Italy 61Department of Astronomy, Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520-8120, USA 62Department of Physics and Department of Astronomy, University of Maryland, College Park, MD 20742, USA 63Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan 64Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata”, I-00133 Roma, Italy 65Center for Cosmology, Physics and Astronomy Department, University of California, Irvine, CA 92697- 2575, USA 66Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA 67Max-Planck-Institut f¨ur Physik, D-80805 M¨unchen, Germany 68Funded by contract FIRB-2012-RBFR12PM1F from the Italian Ministry of Education, University and Research (MIUR) 69Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China 70NYCB Real-Time Computing Inc., Lattingtown, NY 11560-1025, USA 71Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA 72Max-Planck Institut f¨ur extraterrestrische Physik, 85748 Garching, Germany 73Department of Chemistry and Physics, Purdue University Calumet, Hammond, IN 46323-2094, USA 74Institute of Space and Astronautical Science, Japan Aerospace