Speaker
Dr
Joachim Hahn
(MPIK)
Description
Instruments applying the IACT method, such as H.E.S.S. (High Energy Stereoscopic System), observe VHE (very high energy, E>100GeV) photons indirectly, using the Earth's atmosphere as a calorimeter. In the H.E.S.S. data reconstruction, the properties of this component are estimated by Monte Carlo simulations of a yearly averaged atmosphere density profile. Deviations of the real atmospheric conditions from this assumed atmospheric model will result in a biased reconstruction of the primary gamma-ray energy and thus the resulting source spectrum. In order to keep the corresponding systematic effects to a minimum, H.E.S.S. operates a set of atmosphering monitoring devices that allows it to characterise the atmospheric conditions during data taking. This information in turn is then used in data selection. Here, a short overview with respect to their usage during source observation and a posteriori analysis data selection will be presented.
Primary author
Dr
Joachim Hahn
(MPIK)
