The rapid atmospheric monitoring system of the Pierre Auger Observatory

PIERRE AUGER COLLABORATION (J. ABRAHAM, ... , A. MARIAZZI, ET AL)

JOURNAL OF INSTRUMENTATION

IOP PUBLISHING LTD

Lugar: Londres; Año: 2012 vol. 7 p. 1 - 42

1748-0221

The Pierre Auger Observatory is a facility built to detect air showers produced bycosmic rays above 1017 eV. During clear nights with a low illuminated moon fraction, the UV fluorescencelight produced by air showers is recorded by optical telescopes at the Observatory. Tocorrect the observations for variations in atmospheric conditions, atmospheric monitoring is performedat regular intervals ranging from several minutes (for cloud identification) to several hours(for aerosol conditions) to several days (for vertical profiles of temperature, pressure, and humidity).In 2009, the monitoring program was upgraded to allow for additional targeted measurementsof atmospheric conditions shortly after the detection of air showers of special interest, e. g., showersproduced by very high-energy cosmic rays or showers with atypical longitudinal profiles. Theformer events are of particular importance for the determination of the energy scale of the Observatory,and the latter are characteristic of unusual air shower physics or exotic primary particle types.The purpose of targeted (or “rapid”) monitoring is to improve the resolution of the atmosphericmeasurements for such events. In this paper, we report on the implementation of the rapid monitoringprogram and its current status. The rapid monitoring data have been analyzed and appliedto the reconstruction of air showers of high interest, and indicate that the air fluorescence measurementsaffected by clouds and aerosols are effectively corrected using measurements from theregular atmospheric monitoring program. We find that the rapid monitoring program has potentialfor supporting dedicated physics analyses beyond the standard event reconstruction.