1. A 1.8 m class pathfinder Raman LIDAR for the northern site of the Cherenkov Telescope Array Observatory : technical designOtger Ballester, O. Blanch Bigas, Joan Boix, Paolo G. Calisse, Anna Campoy-Ordaz, Sidika Merve Çolak, Darko Kolar, Samo Stanič, Marko Zavrtanik, Miha Živec, 2025, original scientific article Abstract: This paper presents the technical design of the pathfinder Barcelona Raman LIDAR (pbrl) for the northern site of the Cherenkov Telescope Array Observatory (Northern site of the Cherenkov Telescope Array Observatory (CTAO-N)) located at the Roque de los Muchachos Observatory (Roque de los Muchachos Observatory (ORM)). The pBRL is developed for continuous atmospheric characterization, essential for correcting high-energy gamma-ray observations captured by Imaging Atmospheric Cherenkov Telescopes (IACTs). The LIDAR consists of a steerable telescope with a 1.8 m parabolic mirror and a pulsed Nd:YAG laser with frequency doubling and tripling. It emits at wavelengths of 355 nm and 532 nm to measure aerosol scattering and extinction through two elastic and Raman channels. Built upon a former Cherenkov Light Ultraviolet Experiment (Cherenkov Light Ultraviolet Experiment (CLUE)) telescope, the pBRL’s design includes a Newtonian mirror configuration, a coaxial laser beam, a near-range system, a liquid light guide and a custom-made polychromator. During a one-year test at the ORM, the stability of the LIDAR and semi-remote-controlled operations were tested. This pathfinder leads the way to designing a final version of a Cherenkov Telescope Array Observatory (CTAO) Raman LIDAR which will provide real-time atmospheric monitoring and, as such, ensure the necessary accuracy of scientific data collected by the CTAO-N telescope array.
Keywords: Raman LIDAR, design, aerosols, atmospheric effects, gamma-ray astrophysics, IACTs, polychromator, Liquid Light Guide, Licel, PMT
Published in RUNG: 19.03.2025; Views: 377; Downloads: 2
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2. Monte Carlo studies of combined MAGIC and LST1 observationsF. Di Pierro, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: The Cherenkov Telescope Array (CTA) is the next generation very high energy gamma-ray
observatory covering the 20 GeV - 300 TeV energy range with unprecedented sensitivity, angular and energy resolution. With a site in each hemisphere, CTA will provide full-sky coverage. Four Large Size Telescopes (LSTs) in each site will be dedicated to the lowest energy range (20 GeV - 200 GeV). The first LST prototype has been installed at the CTA Northern site (Canary Island of La Palma, Spain) in October 2018 and it had been since then in commissioning phase. LST1 is located at about 100 m from MAGIC, a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes designed to perform gamma-ray astronomy in the energy range from 50 GeV with standard trigger (30 GeV with SumTrigger) to 50 TeV and whose performance is very well established. The co-location of LST1 and MAGIC offers the great opportunity of cross-calibrating the two systems on an event-by-event basis. It will be indeed possible to compare the parameters of the same extensive air shower reconstructed by the two instruments. We investigated the performance that could be reached with combined observations.
Keywords: very-high-energy gamma rays, Cherenkov Telescope Array (CTA) Observatory, Imaging Atmospheric Cherenkov Telescopes (IACTs), Large-Sized Telescopes (LSTs), Monte Carlo studies
Published in RUNG: 15.11.2024; Views: 862; Downloads: 8
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3. The Cherenkov transparency coefficient for the atmospheric monitoring and array calibration at the Cherenkov Telescope Array SouthStanislav Stefanik, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: Reconstruction of energies of very-high-energy γ–rays observed by imaging atmospheric Cherenkov telescopes is affected by changes in the atmospheric conditions and the performance of telescope components. Reliable calibration schemes aimed at these effects are necessary for the forthcoming Cherenkov Telescope Array (CTA) to achieve its goals on the maximally allowed systematic uncertainty of the global energy scale. A possible means of estimating the atmospheric attenuation of Cherenkov light is the method of the Cherenkov transparency coefficient (CTC). The CTC is calculated using the telescope detection rates, dominated by the steady cosmic ray background, while properly correcting for the hardware and observational conditions.
The coefficient can also be used to relatively calibrate the optical throughput of telescopes on the assumption of homogeneous atmospheric transparency above the array. Using Monte Carlo simulations, we investigate here the potential of the CTC method for the atmospheric monitoring and telescope cross-calibration at the CTA array in the southern hemisphere. We focus on the feasibility of the method for the array of telescopes of three sizes in different observation configurations and under various levels of atmospheric attenuation.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, imaging atmospheric Cherenkov telescopes (IACTs), atmospheric monitoring, IACT calibration
Published in RUNG: 14.11.2024; Views: 857; Downloads: 5
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