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Impact of aerosols and adverse atmospheric conditions on the data quality for spectral analysis of the H.E.S.S. telescopes

Hahn, J.; de los Reyes, R.; Bernlöhr, K.; Krüger, P.; Lo, Y.T.E.; Chadwick, P.M.; Daniel, M.K.; Deil, C.; Gast, H.; Kosack, K.; Marandon, V.


J. Hahn

R. de los Reyes

K. Bernlöhr

P. Krüger

Y.T.E. Lo

M.K. Daniel

C. Deil

H. Gast

K. Kosack

V. Marandon


The Earth’s atmosphere is an integral part of the detector in ground-based imaging atmospheric Cherenkov telescope (IACT) experiments and has to be taken into account in the calibration. Atmospheric and hardware-related deviations from simulated conditions can result in the mis-reconstruction of primary particle energies and therefore of source spectra. During the eight years of observations with the High Energy Stereoscopic System (H.E.S.S.) in Namibia, the overall yield in Cherenkov photons has varied strongly with time due to gradual hardware aging, together with adjustments of the hardware components, and natural, as well as anthropogenic, variations of the atmospheric transparency. Here we present robust data selection criteria that minimize these effects over the full data set of the H.E.S.S. experiment and introduce the Cherenkov transparency coefficient as a new atmospheric monitoring quantity. The influence of atmospheric transparency, as quantified by this coefficient, on energy reconstruction and spectral parameters is examined and its correlation with the aerosol optical depth (AOD) of independent MISR satellite measurements and local measurements of atmospheric clarity is investigated.


Hahn, J., de los Reyes, R., Bernlöhr, K., Krüger, P., Lo, Y., Chadwick, P., …Marandon, V. (2014). Impact of aerosols and adverse atmospheric conditions on the data quality for spectral analysis of the H.E.S.S. telescopes. Astroparticle Physics, 54, 25-32.

Journal Article Type Article
Acceptance Date Oct 25, 2013
Publication Date Feb 1, 2014
Deposit Date Apr 15, 2015
Publicly Available Date Apr 20, 2015
Journal Astroparticle Physics
Print ISSN 0927-6505
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 54
Pages 25-32
Keywords Cherenkov telescopes, Gamma-ray astronomy, Aerosols, Atmosphere, MISR, Radiometer.
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