UHE cosmic ray detection with the Pierre Auger Observatory

The Pierre Auger Observatory measures the energy spectrum, the arrival direction, and the mass composition of cosmic rays above 10¹⁸ eV with a hybrid detector system. It will finally consist of an array of 1600 water-Cherenkov surface detectors (SD) on a 1.5 km triangular grid and 24 fluorescence telescopes (FD) in 4 stations on the perimeter of the 3000 km² experimental area. The observatory is at present under construction in the Pampa Amarilla near the town of Malargue - Province of Mendoza, Argentina. The construction of this Southern side will be completed in early 2006. We present the hybrid design of the observatory (SD, FD), the current status of construction and the performance of the experiment gained during regular operation in the installation phase. Since mid 2004 the first half of the FD telescopes is installed and more than one quarter of the SD array is deployed. The observatory will be complemented by a northern experiment in Utah or Colorado to achieve uniform full sky coverage.