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On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

Brown, Anthony M.

On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform Thumbnail


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Abstract

Recent advances in unmanned aerial vehicle (UAV) technology have made UAVs an attractive possibility as an airborne calibration platform for astronomical facilities. This is especially true for arrays of telescopes spread over a large area such as the Cherenkov Telescope Array (CTA). In this paper, the feasibility of using UAVs to calibrate CTA is investigated. Assuming a UAV at 1km altitude above CTA, operating on astronomically clear nights with stratified, low atmospheric dust content, appropriate thermal protection for the calibration light source and an onboard photodiode to monitor its absolute light intensity, inter-calibration of CTA’s telescopes of the same size class is found to be achievable with a 6−8% uncertainty. For cross-calibration of different telescope size classes, a systematic uncertainty of 8−10% is found to be achievable. Importantly, equipping the UAV with a multi-wavelength calibration light source affords us the ability to monitor the wavelength-dependent degradation of CTA telescopes’ optical system, allowing us to not only maintain this 6−10% uncertainty after the first few years of telescope deployment, but also to accurately account for the effect of multi-wavelength degradation on the cross-calibration of CTA by other techniques, namely with images of air showers and local muons. A UAV-based system thus provides CTA with several independent and complementary methods of cross-calibrating the optical throughput of individual telescopes. Furthermore, housing environmental sensors on the UAV system allows us to not only minimise the systematic uncertainty associated with the atmospheric transmission of the calibration signal, it also allows us to map the dust content above CTA as well as monitor the temperature, humidity and pressure profiles of the first kilometre of atmosphere above CTA with each UAV flight.

Citation

Brown, A. M. (2018). On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform. Astroparticle Physics, 97, 69-79. https://doi.org/10.1016/j.astropartphys.2017.10.013

Journal Article Type Article
Acceptance Date Oct 24, 2017
Online Publication Date Nov 7, 2017
Publication Date Jan 1, 2018
Deposit Date Nov 28, 2017
Publicly Available Date Jan 3, 2024
Journal Astroparticle Physics
Print ISSN 0927-6505
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 97
Pages 69-79
DOI https://doi.org/10.1016/j.astropartphys.2017.10.013
Public URL https://durham-repository.worktribe.com/output/1339234

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