114 research outputs found
Pybkgmodel - a background modelling toolbox for the CTA
No full textDespite the advancement in background rejection techniques, observation of the very-high-energy gamma-ray sky by imaging atmospheric Cherenkov telescopes (IACTs) are subject to an irreducible background from gamma-like hadron- or electron-induced air showers. The determination of this residual background is crucial for accurate spectral and spatial measurements. The Cherenkov Telescope Array (CTA) will become the next generation of IACTs. To unveil its full potential, the improved reconstruction performance of CTA needs to be coupled with a reliable background estimate across the entire field of view. This may become especially important in the case of the planned surveys of large areas of the sky. In this contribution we will present pybkgmodel, an open-source python software package developed for CTA. It aims at providing in a consistent way the various background modelling methods, based on the experience from current IACTs such as H.E.S.S, MAGIC, and VERITAS. It is designed as a toolbox allowing a user to easily choose the optimal reconstruction approach for various target regions or a combination of several algorithms. We will introduce the design of the package as well as demonstrate its functionality using data for the CTA Large-Sized Telescope prototype (LST-1). © Copyright owned by the author(s) under the terms of the Creative Commons
lstchain: An Analysis Pipeline for LST-1, the First Prototype Large-Sized Telescope of CTA
No full textInternational audienceThe future Cherenkov Telescope Array (CTA) will have telescopes of different sizes, the Large-Sized Telescopes (LSTs) being the largest ones. Located on the island of La Palma, the LST-1, the prototype of the first LST, started taking astronomical data in November 2019, detecting the first gamma-ray sources right afterwards. The analysis pipeline, that processes data from raw inputs until high level products is called lstchain and is heavily based in the CTA prototype pipeline framework ctapipe. In this presentation I'll show the pipeline that performs signal integration, image cleaning, image parameter calculation, and machine learning methods for true parameter reconstruction
Status and results of the prototype LST of CTA
No full textThe Large-Sized Telescopes (LSTs) of Cherenkov Telescope Array (CTA) are designed for gamma-ray studies focusing on low energy threshold, high flux sensitivity, rapid telescope repositioning speed and a large field of view. Once the CTA array is complete, the LSTs will be dominating the CTA performance between 20 GeV and 150 GeV. During most of the CTA Observatory construction phase, however, the LSTs will be dominating the array performance until several TeVs. In this presentation we will report on the status of the LST-1 telescope inaugurated in La Palma, Canary islands, Spain in 2018. We will show the progress of the telescope commissioning, compare the expectations with the achieved performance, and give a glance of the first physics results
Cross-calibration and combined analysis of the CTA-LST prototype and the MAGIC telescopes
No full textThe Cherenkov Telescope Array (CTA) is the next-generation gamma-ray observatory that is
expected to reach one order of magnitude better sensitivity than that of current telescope arrays.
The Large-Sized Telescopes (LSTs) have an essential role in extending the energy range down to
20 GeV. The prototype LST (LST-1) proposed for CTA was built in La Palma, the northern site
of CTA, in 2018. LST-1 is currently in its commissioning phase and moving towards scientific
observations. The LST-1 camera consists of 1855 photomultiplier tubes (PMTs) which are
sensitive to Cherenkov light. PMT signals are recorded as waveforms sampled at 1 GHz rate with
Domino Ring Sampler version 4 (DRS4) chips. Fast sampling is essential to achieve a low energy
threshold by minimizing the integration of background light from the night sky. Absolute charge
calibration can be performed by the so-called F-factor method, which allows calibration constants
to be monitored even during observations. A calibration pipeline of the camera readout has been
developed as part of the LST analysis chain. The pipeline performs DRS4 pedestal and timing
corrections, as well as the extraction and calibration of charge and time of pulses for subsequent
higher-level analysis. The performance of each calibration step is examined, and especially charge
and time resolution of the camera readout are evaluated and compared to CTA requirements. We
report on the current status of the calibration pipeline, including the performance of each step
through to signal reconstruction, and the consistency with Monte Carlo simulation
Cross-calibration and combined analysis of the CTA-LST prototype and the MAGIC telescopes
No full textThe Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory, which will consist of three kinds of telescopes of different sizes. Among those, the Large Size Telescope (LST) will be the most sensitive in the low energy range starting from 20 GeV. The prototype LST (LST-1) proposed for CTA was inaugurated in October 2018 in the northern hemisphere site, La Palma (Spain), and is currently in its commissioning phase. MAGIC is a system of two gamma-ray Cherenkov telescopes of the current generation, located approximately 100 m away from LST-1, that have been operating in stereoscopic mode since 2009. Since LST-1 and MAGIC can observe the same air shower events, we can compare the brightness of showers, estimated energies of gamma rays, and other parameters event by event, which can be used to cross-calibrate the telescopes. Ultimately, by performing combined analyses of the events triggering the three telescopes, we can reconstruct the shower geometry more accurately, leading to better energy and angular resolutions, and a better discrimination of the background showers initiated by cosmic rays. For that purpose, as part of the commissioning of LST-1, we performed joint observations of established gamma-ray sources with LST-1 and MAGIC. Also, we have developed Monte Carlo simulations for such joint observations and an analysis pipeline which finds event coincidence in the offline analysis based on their timestamps. In this work, we present the first detection of an astronomical source, the Crab Nebula, with combined observation of LST-1 and MAGIC. Moreover, we show results of the inter-telescope cross-calibration obtained using Crab Nebula data taken during joint observations with LST-1 and MAGIC
LST-1 observations of an enormous flare of BL Lacertae in 2021
No full textInternational audienceThe first prototype of LST (LST-1) for the Cherenkov Telescope Array has been in commissioning phase since 2018 and already started scientific observations with the low energy threshold around a few tens of GeV. In 2021, LST-1 observed BL Lac following the alerts based on multi-wavelength observations and detected prominent gamma-ray flares. In addition to the daily flux variability, LST-1 also detected sub-hour-scale intra-night variability reaching 3–4 times higher than thegamma-ray flux from the Crab Nebula above 100 GeV. In this proceeding, we will report the analysis results of LST-1 observations of BL Lac in 2021, especially focusing on flux variability
LST-1 observations of an enormous flare of BL Lacertae in 2021
No full text38th International Cosmic Ray Conference (ICRC2023), 26 July - 3 August, 2023, Nagoya, Japan.Seiya Nozaki, Katsuaki Asano, Juan Escudero, Gabriel Emery and Chaitanya Priyadarshi on behalf of the CTA-LST Project.
Luis del Peral Gochicoa, Jose Julio Lozano Bahilo and Maria Dolores Rodriguez Frias belong to the CTA-LST Project.The first prototype of LST (LST-1) for the Cherenkov Telescope Array has been in commissioning
phase since 2018 and already started scientific observations with the low energy threshold around
a few tens of GeV. In 2021, LST-1 observed BL Lac following the alerts based on multi-wavelength
observations and detected prominent gamma-ray flares. In addition to the daily flux variability,
LST-1 also detected sub-hour-scale intra-night variability reaching 3–4 times higher than the
gamma-ray flux from the Crab Nebula above 100 GeV. In this proceeding, we will report the
analysis results of LST-1 observations of BL Lac in 2021, especially focusing on flux variability
Physics Performance of the Large-Sized Telescope prototype of the Cherenkov Telescope Array
No full textInternational audienceThe Large-Sized Telescope (LST) prototype of the future Cherenkov Telescope Array (CTA) is located at the Northern site of CTA, on the Canary Island of La Palma. It is designed to provide optimal performance in the lowest part of the energy range covered by CTA, observing gamma rays down to energies of tens of GeV. The LST prototype started performing astronomical observations in November 2019 during the commissioning of the telescope and it has been taking data since then. In this contribution, we will present the tuning of the characteristics of the telescope in the Monte Carlo (MC) simulations to describe the data obtained, the estimation of its angular and energy resolution, and an evaluation of its sensitivity, both with simulations and with observations of the Crab Nebula
R&D of an active mirror control system of the large telescope for the CTA project
No full text研究成果の概要（和文）：CTA計画のLSTは20GeVの閾値を持つガンマ線観測装置である。198枚の六角形分割鏡から構成され，AMCシステムにより常時能動的に方向制御される。構成する個々の分割鏡はアクチュエータ，CMOSカメラ，レーザにより光軸の向きを補正する。ここ3年をかけてAMCシステムを開発してきた結果，光軸の向きを2秒角の高性能で制御する事を達成した。この値は当初の目標である14秒角を大きく上回る性能である。更に，198枚の分割鏡を同時に制御するための拡張AMCのアルゴリズムを，全ての鏡を十枚程に分ける方法を採ることにより開発した。鏡とAMCシステムはラパルマに建設中のLST第1号機に組み込む予定である。
研究成果の概要（英文）： The LST of the CTA is designed to achieve a threshold energy of 20GeV for HE gamma rays. The dish of the LST is composed of 198 hexagonal 1.5m mirrors. The mirror facets are actively aligned during operations by an AMC system. To correct a direction of the optical axis of a each mirror facet, the AMC system uses two actuators, a CMOS camera, and a reference laser. The AMC system has been developed for these three years and achieved a high performance of 2 arcsec to control optical axis direction. This specification is exceeded our original goal of 14 arcsec. Furthermore an algorithm for extended AMC system was developed to control 198 mirrors on the LST simultaneously by method of clusterised all mirrors divided into ten mirrors in each group. The mirrors with the AMC system is expected to install a first LST at La Palma in early 2017. This work was supported by JSPS KAKENHI Number 25287063, and gratefully acknowledge to the organizations of Max-Planck-Society, and U. Zurich.研究種目：基盤研究(B); 研究期間：2013～2015; 課題番号：25287063; 研究分野：宇宙粒子線実験物理学; 科研費の分科・細目：Research Paperapplication/pdfresearch repor
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