Fluorescence and Hybrid Detection Aperture of the Pierre Auger   Observatory
  The aperture of the Fluorescence Detector (FD) of the Pierre Auger Observatory is evaluated from simulated events using different detector configurations: mono, stereo, 3-FD and 4-FD. The trigger efficiency has been modeled using shower profiles with ground impacts in the field of view of a single telescope and studying the trigger response (at the different levels) by that telescope and by its neighbours. In addition, analysis cuts imposed by event reconstruction have been applied. The hybrid aperture is then derived for the Auger final extension. Taking into account the actual Surface Detector (SD) array configuration and its trigger response, the aperture is also calculated for a typical configuration of the present phase. 
J.A. Bellido, D. D'Urso, H. Geenen, F. Guarino, L. Perrone, S.   Petrera, L. Prado Jr., F. Salamida