Covino, S.. INAF National Institute for Astrophysics, I-00136 Rome, Italy
Da Vela, P.. Università di Siena, and INFN Pisa, I-53100 Siena, Italy
Dazzi, F.. Max-Planck-Institut für Physik, D-80805München, Germany
De Angelis, A.. Università di Udine, and INFN Trieste, I-33100 Udine, Italy
De Caneva, G.. Deutsches Elektronen-Synchrotron (DESY), D-15738 Zeuthen, Germany
De Lotto, B.. Università di Udine, and INFN Trieste, I-33100 Udine, Italy
de Oña Wilhelmi, E.. Institute of Space Sciences, E-08193 Barcelona, Spain
Delgado Mendez, C.. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, E-28040 Madrid, Spain
Dominis Prester, D.. Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia
Dorner, D.. Universität Würzburg, D-97074Würzburg, Germany
Doro, M.. Università di Padova and INFN, I-35131 Padova, Italy
Einecke, S.. Technische Universität Dortmund, D-44221 Dortmund, Germany
Eisenacher, D.. Universität Würzburg, D-97074Würzburg, Germany
Elsaesser, D.. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, E-28040 Madrid, Spain
Fidalgo, D.. Universidad Complutense, E-28040 Madrid, Spain
Fonseca, M. V.. Universidad Complutense, E-28040 Madrid, Spain
Font, L.. Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
Frantzen, K.. Technische Universität Dortmund, D-44221 Dortmund, Germany
Fruck, C.. Max-Planck-Institut für Physik, D-80805München, Germany
Galindo, D.. Universitat de Barcelona, ICC, IEEC-UB, E-08028 Barcelona, Spain
García López, R. J.. Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
Garczarczyk, M.. Deutsches Elektronen-Synchrotron (DESY), D-15738 Zeuthen, Germany
Garrido Terrats, D.. Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
Gaug, M.. Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
Godinović, N.. Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia
PG 1553+113 is a very high energy (VHE, E>100 GeV) γ-ray emitter classified as a BL Lac object. Its redshift is constrained by intergalactic absorption lines in the range 0.4