The fluorescence detector of the Pierre Auger Observatory Pierre Auger Collaboration Bueno Villar, Antonio García Gámez, Diego González, J. L. Lozano Bahílo, Julio Navarro, J. Navas Concha, Sergio Cosmic rays Fluorescence detector The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions. 2013-11-08T11:24:19Z 2013-11-08T11:24:19Z 2009 info:eu-repo/semantics/article Pierre Auger Observatory. The fluorescence detector of the Pierre Auger Observatory. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 620(2-3): 227-251 (2010). [http://hdl.handle.net/10481/29085] 0168-9002 doi: 10.1016/j.nima.2010.04.023 arXiv:0907.4282v1 http://hdl.handle.net/10481/29085 eng info:eu-repo/grantAgreement/EC/FP7/220240 http://creativecommons.org/licenses/by-nc-nd/3.0/ info:eu-repo/semantics/openAccess Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Elsevier