The Cosmic Ray Background as a Tool for Relative Calibration of Atmospheric Cherenkov Telescopes

Abstract

The atmosphere is an intrinsic part of any ground based Cherenkov gamma-ray telescope, and the telescope response is therefore sensitive to unpredictable changes in the atmospheric transparency which are difficult to measure and interpret in the absence of a calibrated beam of high energy gamma-rays. In this paper, we use the detector response to Cherenkov emission from cosmic ray initiated air showers to obtain a relative calibration for data obtained under different instrumental and atmospheric conditions as well as over a range of source angles to the Zenith. We show that such a relative calibration is useful and efficient for data selection, for correcting the measured gamma-ray rate and for inter-calibration between the elements of an array of Cherenkov telescopes.

19 pages. Accepted for publication in Astroparticle Physics

References in corpus (4)

• VERITAS: the Very Energetic Radiation Imaging Telescope Array System
• Temporal and spectral gamma-ray properties of Mkn421 above 250 GeV from CAT observations between 1996 and 2000
• Detection of the BL Lac Object H1426+428 at TeV Gamma Ray Energies
• Measurement of the Crab Flux Above 60 GeV with the CELESTE Cherenkov Telescope

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