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Colin Carlile, researcher at Lund Observatory. Photo.

Colin Carlile

Guest researcher

Colin Carlile, researcher at Lund Observatory. Photo.

Performance of the Cherenkov Telescope Array in the presence of clouds

Author

  • M. Pecimotika
  • Katarzyna Adamczyk
  • Dijana Dominis Prester
  • Orel Gueta
  • Dario Hrupec
  • Gernot Maier
  • Saša Mićanović
  • Lovro Pavletić
  • Julian Sitarek
  • Dorota Sobczyńska
  • Michał Szanecki
  • C. Carlile
  • D. Dravins
  • A. Zmija
Show all

Summary, in English

The Cherenkov Telescope Array (CTA) is the future ground-based observatory for gamma-ray astronomy at very high energies. The atmosphere is an integral part of every Cherenkov telescope. Different atmospheric conditions, such as clouds, can reduce the fraction of Cherenkov photons produced in air showers that reach ground-based telescopes, which may affect the performance. Decreased sensitivity of the telescopes may lead to misconstructed energies and spectra. This study presents the impact of various atmospheric conditions on CTA performance. The atmospheric transmission in a cloudy atmosphere in the wavelength range from 203 nm to 1000 nm was simulated for different cloud bases and different optical depths using the MODerate resolution atmospheric TRANsmission (MODTRAN) code. MODTRAN output files were used as inputs for generic Monte Carlo simulations. The analysis was performed using the MAGIC Analysis and Reconstruction Software (MARS) adapted for CTA. As expected, the effects of clouds are most evident at low energies, near the energy threshold. Even in the presence of dense clouds, high-energy gamma rays may still trigger the telescopes if the first interaction occurs lower in the atmosphere, below the cloud base. A method to analyze very high-energy data obtained in the presence of clouds is presented. The systematic uncertainties of the method are evaluated. These studies help to gain more precise knowledge about the CTA response to cloudy conditions and give insights on how to proceed with data obtained in such conditions. This may prove crucial for alert-based observations and time-critical studies of transient phenomena. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0)

Department/s

  • Lund Observatory - Has been reorganised

Publishing year

2022

Language

English

Publication/Series

Proceedings of Science

Volume

395

Document type

Conference paper

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Cosmic rays
  • Cosmology
  • Gamma rays
  • Intelligent systems
  • Light transmission
  • Telescopes
  • Atmospheric conditions
  • Atmospheric transmissions
  • Cherenkov telescope arrays
  • Cloud base
  • Gamma-ray astronomy
  • Ground based observatories
  • Integral part
  • Moderate resolution
  • Performance
  • Very high energies
  • Monte Carlo methods

Conference name

37th International Cosmic Ray Conference

Conference date

2021-07-12 - 2021-07-23

Conference place

Berlin, Germany

Status

Published

ISBN/ISSN/Other

  • ISSN: 1824-8039