Measurements of the optical properties of the Auger fluorescence telescopes

THE PIERRE AUGER COLLABORATION.; S. J. SCIUTTO

Conferencia; 33rd International Cosmic Ray Conference; 2013

Fluorescence telescopes are used for the calorimetric measurement of the energy of air showers atthe Pierre Auger Observatory. The optical properties of these telescopes have to be known precisely to allow foran absolute energy calibration. We present a method to measure their light distribution function independent ofshower data. We have developed an isotropic, point-like light source, that was brought into the field of view ofa telescope using an autonomously flying platform, an octocopter. The optical properties of the telescopes areprobed in detail by illuminating the telescopes from different angles with respect to the telescope axis and byobscuring or removing certain telescope components. In this contribution, we describe the light source which wasdeveloped and the important properties of the octocopter. We further present the first results on the measured lightdistribution and compare them to detailed telescope simulations.