The Pierre Auger Observatory is the world's largest detector for exten-
sive air showers initiated by cosmic rays with energies above 3 x 1017 eV.
Equipped with 1660 water-Cherenkov stations, the surface detector array
spans an area of 3000km2. The combination with 27
which overlook the atmosphere and measure the calorimetric energy allows
for a hybrid detection. The all-sky flux of cosmic rays is obtained by com-
bining four independent data sets. The surface detector array provides three data sets, two formed by dividing the data into two zenith angle ranges, and one obtained from a nested, denser detector array. The fourth measurement is obtained with the fluorescence detector. In this talk, the spectral Features are discussed in detail and the systematic uncertainties are addressed.