This extensive paper concisely describes all components of the fluorescence detector of the Pierre Auger Observatory including its optical system, the design of the camera, the electronics and the systems for relative and absolute calibrations. The operation and the monitoring of the detector are discussed and the detector performance and precision of shower reconstruction is evaluated. The paper is the major reference to the currently largest system of fluorescence telescopes ever built.
The article was created under the leadership of the Prague group and includes the activities of all international institutions collaborating on the fluorescence detector. To publish such a reference paper was one of the ambitions of the Prague group and we have contributed substantially to the text editing and coordination of the effort.