1. 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: 261; Downloads: 4
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2. 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: 284; Downloads: 4
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3. Using muon rings for the optical throughput calibration of the Cherenkov Telescope ArrayMarkus Gaug, 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: Muon ring images observed with Imaging Atmospheric Cherenkov Telescopes (IACTs) provide a powerful means to calibrate the optical throughput of IACTs and monitor their optical point spread function. We investigate whether muons ring images can be used as the primary optical throughput calibration method for the telescopes of the future Cherenkov Telescope Array (CTA) and find several additional systematic effects in comparison to previous works. To ensure that the method achieves the accuracy required by CTA, these systematic effects need to be taken into account and minor modifications to the hardware and analysis are necessary. We derive analytic estimates for the expected muon data rates to be used for optical throughput calibration, monitoring of the optical point spread function, with achievable statistical and systematic uncertainties, and explore the potential of muon ring images as a secondary method of camera pixel flat-fielding.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, Imaging Atmospheric Cherenkov Telescopes, IACT optical throughput calibration, IACT camera pixel flat-fielding, IACT optical point spread function (PSF), muon ring images
Published in RUNG: 13.11.2024; Views: 275; Downloads: 5
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4. Status and performance results from NectarCAM : a camera for CTA medium sized telescopesThomas Tavernier, 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) will be the first ground-based observatory for gamma-ray astronomy. With more than a hundred of 4th generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) distributed in two large arrays, CTA will reach unprecedented sensitivity, angular resolution, and spectral coverage. Three classes of IACTs – 40 Medium-Sized Telescopes (MSTs), 8 Large-Sized Telescopes (LSTs) and 70 Small-Sized Telescopes (SSTs) – are required to cover the full CTA energy range (20 GeV to 300 TeV).
NectarCAM is a Cherenkov camera which is designed to equip medium sized telescopes of CTA, covering the central energy range from 100 GeV to 30 TeV, with a field of view of 8 degrees. It is based on a modular design with data channels using the NECTAr chip, which is equipped with both GHz sampling Switched Capacitor Array and 12-bit Analog to Digital Converter (ADC). The camera will comprise 265 modules, each consisting of 7 photomultiplier Tubes (PMTs) and a Front-End Board performing the data capture, sending the data over the Ethernet after the trigger decision at rates up to 10 kHz.
This contribution provides an overview of the status of the first NectarCAM camera currently under integration in CEA Paris-Saclay (France). Furthermore, we will discuss the calibration strategies and present performance results from the CEA Paris-Saclay test bench and from the first data taken under a real sky on the prototype of medium sized telescope (MST) structure in Adlershof (Germany).
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, Imaging Atmospheric Cherenkov Telescopes, medium-sized telescopes, NectarCAM IACT camera
Published in RUNG: 13.11.2024; Views: 316; Downloads: 4
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