Correcting Imaging Atmospheric Cherenkov Telescope data with atmospheric profiles obtained with an elastic light detecting and ranging system

Schmuckermaier, F.; Gaug, M.; Fruck, C.; Moralejo, A.; Hahn, A.; Prester, D. Dominis; Dorner, D.; Font, L.; Micanovic, S.; R., Mirzoyan,; Paneque, D.; Pavletic, L.; Sitarek, J.; Will, M.

doi:10.1051/0004-6361/202245787

Cited by 9 publications

(8 citation statements)

References 67 publications

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“…To reduce systematic uncertainties arising from atmospheric conditions, the MAGIC collaboration operates an elastic LIDAR (LIght Detection And Ranging) system [23]. This enables data corrections based on atmospheric transmission profiles [24].…”

Section: Observational Strategiesmentioning

confidence: 99%

Highlights of the Magic Florian Goebel Telescopes in the Study of Active Galactic Nuclei

Manganaro,

Dominis Prester

2024

Universe

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The MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) Florian Goebel telescopes are a system of two Cherenkov telescopes located on the Canary island of La Palma (Spain), at the Roque de Los Muchachos Observatory, which have been operating in stereo mode since 2009. Their low energy threshold (down to 15 GeV) allows the investigation of Active Galactic Nuclei (AGNs) in the very-high-energy (VHE, E > 100 GeV) gamma-ray range with a sensitivity up to the redshift limit of the existing IACT (Imaging Atmospheric Cherenkov Telescopes) systems. The MAGIC telescopes discovered 36 extragalactic objects emitting VHE gamma-rays and performed comprehensive studies of galaxies and their AGNs, also in a multi-wavelength (MWL) and multi-messenger (MM) context, expanding the knowledge of our Universe. Here, we report on the highlights achieved by the MAGIC collaboration since the beginning of their operations.

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Section: Observational Strategiesmentioning

confidence: 99%

Highlights of the Magic Florian Goebel Telescopes in the Study of Active Galactic Nuclei

Manganaro,

Dominis Prester

2024

Universe

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“…In case of Cherenkov telescopes, lidars can be used to observe the atmospheric conditions close to the field of view of the Cherenkov telescopes, providing adequate atmospheric information without interfering the main observations of the observatory. At the MAGIC observatory for detecting gamma rays, an elastic lidar is operated quasi-continuously during MAGIC data taking since 2015 [57]. The lidar follows the MAGIC telescope tracking direction within ∼ 5 • distance.…”

Section: Pos(icrc2023)021mentioning

confidence: 99%

“…The upper example is for favorable conditions where a structured cloud layer is detected between about 9 to 11 km, and the lower example depicts unfavorable conditions with strong cloud interference at a broad range in altitude. From [57]. At observatories using fluorescence telescopes also bi-static elastic lidars are used.…”

Section: Pos(icrc2023)021mentioning

confidence: 99%

Atmospheric Monitoring for Astroparticle Physics Observatories

Keilhauer

2023

Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)

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For many observatories recording high-energy cosmic rays, gamma rays, or neutrinos, the Earth's atmosphere is either an integral part or at least a considerable aspect of the detector setup. After giving an overview of the influence of the atmosphere and its variability on the development of the observed particle cascades and the signals detected from them, atmospheric monitoring strategies implemented by the different observatories are described. Examples of the impact of atmospheric parameters and profiles on the core data of these observatories are given and technical aspects of long-term and partially very laborious monitoring efforts of the Earth's atmosphere are discussed. Due to the per se interdisciplinary character of atmospheric monitoring in astroparticle physics, several new projects beyond the core physics of the astroparticle physics observatories have evolved and some are reviewed in this presentation.

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“…Using LIDAR devices, it is possible to evaluate the transparency of the atmosphere at different heights and, in the case of currently operating observatories, to correct the reconstructed energy and spectral parameters (see e.g. Nolan et al 2010;Devin et al 2019;Dorner et al 2009;Fruck & Gaug 2015;Schmuckermaier et al 2022Schmuckermaier et al , 2023. This information can be used in two different ways.…”

Section: Introductionmentioning

confidence: 99%

“…However, this approach is difficult to realise, as cloud conditions can change on even very short timescales of minutes. Schmuckermaier et al (2023) estimate that less than 22-44% of cloud observations are hampered by rapid cloud movement. The generation of dedicated MC simulations for fine time bins would require huge computer resources and is therefore not feasible.…”

Section: Introductionmentioning

confidence: 99%

A novel image-correction method for cloud-affected observations with Imaging Atmospheric Cherenkov Telescopes

Żywucka,

Sitarek,

Sobczyńska

et al. 2024

A&A

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The presence of clouds during observations with Imaging Atmospheric Cherenkov Telescopes can strongly affect the performance of the instrument due to additional absorption of light and scattering of light beyond the field of view of the instrument. If not corrected for, the presence of clouds leads to increased systematic errors in the results. One approach to correct for the effects of clouds is to include clouds in Monte Carlo simulations to produce models for primary particle classification, and energy and direction estimation. However, this method is challenging due to the dynamic nature of cloudy conditions and requires extensive computational resources. The second approach focuses on correcting the data themselves for cloud effects, which allows the use of standard simulations. However, existing corrections often prioritise the limitation of systematic errors without optimising overall performance. By correcting the data already at the image level, it is possible to improve event reconstruction without the need for specialised simulations. We introduce a novel analysis method based on a geometrical model that can correct the data already at the image level given a vertical transmission profile of a cloud. Using Monte Carlo simulations of an array of four of the Large-Sized Telescopes of the Cherenkov Telescope Array, we investigated the effect of the correction on the image parameters and the performance of the system. We compared the data correction at the camera level with the use of dedicated simulations for clouds with different transmissions and heights. The proposed method efficiently corrects the extinction of light in clouds, eliminating the need for dedicated simulations. Evaluation using Monte Carlo simulations demonstrates improved gamma-ray event reconstruction and overall system performance. Currently used analysis methods for cloud-affected data focus on the correction of the reconstructed energy, however, do not counteract the worsening of the performance parameters. We introduce a novel analysis method, based on a geometrical model that can correct the data already at the image level given a vertical transmission profile of a cloud. Using Monte Carlo simulations of an array of four Large-Sized Telescopes, we investigate the effect of the correction on the image parameters and the performance of the system. The proposed method can efficiently correct the effect of light extinction in the cloud without the need to generate dedicated simulations.

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Correcting Imaging Atmospheric Cherenkov Telescope data with atmospheric profiles obtained with an elastic light detecting and ranging system

Cited by 9 publications

References 67 publications

Highlights of the Magic Florian Goebel Telescopes in the Study of Active Galactic Nuclei

Highlights of the Magic Florian Goebel Telescopes in the Study of Active Galactic Nuclei

Atmospheric Monitoring for Astroparticle Physics Observatories

A novel image-correction method for cloud-affected observations with Imaging Atmospheric Cherenkov Telescopes

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