Using reference stars for verification of the end-to-end absolute calibration and the long term monitoring of the Fluorescence Detector of the Pierre Auger Observatory

Abstract

The absolute calibration of the fluorescence detector telescopes of the Pierre Auger Observatory is an important element for correctly determining the energy of primary cosmic rays producing extensive air showers in the atmosphere. In this contribution we show that signals generated by stars traversing the field of view of the fluorescence detectors can effectively be used as a tool to verify their absolute calibration without requiring any dedicated external hardware device. After describing the details of the procedure we report on the preliminary results obtained by the analysis of signals from reference stars as observed by the fluorescence detector telescopes.