The exposure of the hybrid detector of the Pierre Auger Observatory


P. Abreu, Instituto Superior Técnico
M. Aglietta, Università degli Studi di Torino
E. J. Ahn, Fermi National Accelerator Laboratory
D. Allard, APC - AstroParticule et Cosmologie
I. Allekotte, Centro Atomico Bariloche
J. Allen, New York University
J. Alvarez Castillo, Universidad Nacional Autónoma de México
J. Alvarez-Muñiz, Universidad de Santiago de Compostela
M. Ambrosio, Università degli Studi di Napoli Federico II
A. Aminaei, Radboud University Nijmegen
L. Anchordoqui, University of Wisconsin-Milwaukee
S. Andringa, Instituto Superior Técnico
T. Antičić, Institute Ruder Boskovic
A. Anzalone, INAF Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo
C. Aramo, Università degli Studi di Napoli Federico II
E. Arganda, Universidad Complutense de Madrid
K. Arisaka, University of California, Los Angeles
F. Arqueros, Universidad Complutense de Madrid
H. Asorey, Centro Atomico Bariloche
P. Assis, Instituto Superior Técnico
J. Aublin, Laboratoire de Physique Nucléaire et de Hautes Energies
M. Ave, Karlsruhe Institute of Technology, Campus North
M. Avenier, Laboratoire de Physique Subatomique et de Cosmologie de Grenoble
G. Avila, Pierre Auger Observatory
T. Bäcker, Universität Siegen
D. Badagnani, Universidad Nacional de La Plata
M. Balzer, Karlsruhe Institute of Technology
K. B. Barber, The University of Adelaide
A. F. Barbosa, Centro Brasileiro de Pesquisas Físicas
R. Bardenet, Laboratoire de l'Accélérateur Linéaire
S. L.C. Barroso, Universidade Estadual do Sudoeste da Bahia
B. Baughman, The Ohio State University

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The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The "hybrid" detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. We discuss the relevance of monitoring data collected during operations, such as the status of the fluorescence detector, background light and atmospheric conditions, that are used in both simulation and reconstruction. © 2010 Elsevier B.V. All rights reserved.

Publication Title

Astroparticle Physics