Inter-calibration of atmospheric Cherenkov telescopes with UAV-based airborne calibration system

Brown, Anthony M.; Muller, Jacques; de Naurois, Mathieu; Clark, Paul

Abstract

The recent advances in the flight capability of remotely piloted aerial vehicles (here after referred to as UAVs) have afforded the astronomical community the possibility of a new telescope calibration technique: UAV-based calibration. Building upon a feasibility study which characterised the potential that a UAV-based calibration system has for the future Cherenkov Telescope Array, we created a first-generation UAV-calibration prototype and undertook a field-campaign of inter-calibrating the sensitivity of the H.E.S.S. telescope array with two successful calibration flights. In this paper we report the key results of our first test campaign: firstly, by comparing the intensity of the UAV-calibration events, as recorded by the individual HESS-I cameras, we find that a UAV-based inter-calibration is consistent with the standard muon inter-calibration technique at the level of \SI{5.4}{\%} and \SI{5.8}{\%} for the two individual UAV-calibration runs. Secondly, by comparing the position of the UAV-calibration signal on the camera focal plane, for a variety of telescope pointing models, we were able to constrain the pointing accuracy of the HESS-I telescopes at the tens of arc-second accuracy level. This is consistent with the pointing accuracy derived from other pointing calibration methods. Importantly both the inter-calibration and pointing accuracy results were achieved with a first-generation UAV-calibration prototype, which eludes to the potential of the technique and highlights that a UAV-based system is a viable calibration technique for current and future ground-based γ-ray telescope arrays.

Citation

Brown, A. M., Muller, J., de Naurois, M., & Clark, P. (2022). Inter-calibration of atmospheric Cherenkov telescopes with UAV-based airborne calibration system. Astroparticle Physics, 140, Article 102695. https://doi.org/10.1016/j.astropartphys.2022.102695

• Journal Article Type: Article
• Acceptance Date: Feb 7, 2022
• Online Publication Date: Feb 24, 2022
• Publication Date: 2022-07
• Deposit Date: Jun 13, 2022
• Publicly Available Date: Feb 24, 2023
• Journal: Astroparticle Physics
• Print ISSN: 0927-6505
• Electronic ISSN: 1873-2852
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 140
• Article Number: 102695
• DOI: https://doi.org/10.1016/j.astropartphys.2022.102695
• Public URL: https://durham-repository.worktribe.com/output/1201258
• Related Public URLs: https://arxiv.org/abs/2203.05839