Atmospheric aerosol characterization using the central laser facility at the Pierre Auger Observatory

The Fluorescence Detector of the Pierre Auger Observatory uses the atmosphere as a huge calorimeter that needs continuous monitoring to ensure unbiased physics results. The Central Laser Facility (CLF), a calibrated laser source located near the center of the observatory, is used to measure the light attenuation due to aerosols, highly variable even on time scales of 1 h. Two independent, fully compatible procedures based on the analysis of CLF vertical events have been developed. Five years of hourly aerosol characterization are provided.