Search

This paper summarizes the status and the recent measurements from the Pierre Auger Observatory. The energy spectrum is described and its features discussed. We report searches for anisotropy of cosmic ray arrival directions on large scales and through correlation with catalogues of celestial objects. We also present the search for anisotropies in the data without the use of astronomical catalogues. The first measurement of the proton-air cross section around 10^{18} eV is discussed. Finally, the mass composition is addressed with measurements of the variation of the depth of shower maximum with energy and with the muon density at ground., Comment: Prepared for a special topical issue of Advances in Space Research (ASR) entitled "Cosmic Ray Origins: Viktor Hess Centennial Anniversary". Presented at COSPAR 2012, Mysore, India

We report a measurement of the cosmic ray energy spectrum based on a large amount of data collected by the Pierre Auger Observatory. This measurement combines data from the fluorescence (FD) and surface (SD) detectors of the Observatory and does not rely on detailed numerical simulation or any assumption about the chemical composition. The energy calibration of the observables, which exploits the correlation of surface detector data with fluorescence measurements in hybrid events, is presented in detail. Besides presenting statistical uncertainties, we address the impact of systematic uncertainties. We also summarize the combined energy spectrum obtained when hybrid data are used to extend the spectrum to lower energies.