Atmospheric monitoring with the LIDAR network of the Pierre Auger Observatory

The Pierre Auger Observatory, recently completed, is designed to detect ultra high energy cosmic rays with two different techniques. One of these is based on air fluorescence detection, and needs a constant and precise characterization of the atmospheric properties. A system of four steerable LIDARs, one for each fluorescence detector site, has been designed for this task. This paper describes the hardware design, the current scanning procedure, and the analyses performed on the data collected.