Performance of the Pierre Auger Fluorescence Detector and Analysis of well recontructed events

The Pierre Auger Observatory is designed to elucidate the origin and nature of Ultra High Energy Cosmic Rays using a hybrid detection technique. A first run of data taking with a prototype version of both detectors (the so called Engineering Array) took place in 2001-2002, allowing the Collaboration to evaluate the performance of the two detector systems and to approach an analysis strategy. In this contribution, after a brief description of the system, we will report some results on the behavior of the Fluorescence Detector (FD) Prototype. Performance studies, such as measurements of noise, sensitivity and duty cycle, will be presented. We will illustrate a preliminary analysis of selected air showers. This analysis is performed using exclusively the information from the FD, and includes reconstruction of the shower geometry and of the longitudinal profil

The Anisotropy Search Program For the Pierre Auger Observatory

The Pierre Auger Southern Observatory in Argentina has begun taking data as it is being developed up to a final enclosed area of 3000 square kilometres. A key aspect of the project is to provide information on the origin of the highest energy cosmic rays through understanding the arrival directions of those particles. To avoid claims of a spurious anisotropy detection because trials have not been properly accounted, the Auger Collaboration has agreed 'a priori' to the analysis prescription presented here. It specifies the following: 1. The accumulation time for the (future) data set to be analyzed. 2. The anisotropy 'targets', each assigned a chance probability level. 3. The analysis procedure for each trial. A positive result will be claimed for any target search only if its chance probability is less than its assigned level. The levels are chosen so that the total chance probability for one or more positive results is 0.001. Exploratory searches beyond this prescription will be encouraged, but the Auger Collaboration will not assign any confidence level to anisotropies that may be discovered that way. Any such discovery would identify a good target for a prescription to be used with a subsequent Auger data set

A Study Of Very Inclined Showers In The Pierre Auger Observatory

The Engineering Array of the Auger Observatory has been running successfully since 2001 and inclined showers have been recorded from the start. We have analysed the events with zenith angle $>$ 70$^0$ recorded between May and November 2002. The different algorithms developed to analyze these showers are also discussed. An preliminary discussion of a reconstructed event having 20 detectors hit is presented. Inclined showers will be detected by the full Auger Observatory and they will allow significant enhancement of the array aperture. High energy events will be seen as spectacular events with 30 or 40 tanks triggered and they will provide alternative information on muon content in air showers