2,267 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
The Cerenkov telescope array project status
No full textThe Cherenkov Telescope Array (CTA) represents the next generation ground-based observatory for gamma-ray astronomy at very-high energies. It will be capable of detecting gamma rays in the energy range from 20 GeV to more than 300 TeV with unprecedented precision in energy and directional reconstruction. CTA will be located in the northern hemisphere at La Palma, Spain, and in the southern hemisphere at Paranal, Chile, and will comprise more than 100 telescopes of three different types. CTA will be one of the largest astronomical infrastuctures in the world with open data access and it will address questions in astronomy, astrophysics and fundamental physics in the next decades. In this contribution we will present the status of the CTA construction, discuss the telescope prototypes, highlight the scientific perspectives and the instrument performances
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
Reconstruction of stereoscopic CTA events using deep learning with CTLearn [Elektronisk resurs]
No full textThe Cherenkov Telescope Array (CTA), conceived as an array of tens of imaging atmospheric Cherenkov telescopes (IACTs), is an international project for a next-generation ground-based gamma-ray observatory, aiming to improve on the sensitivity of current-generation instruments a factor of five to ten and provide energy coverage from 20 GeV to more than 300 TeV. Arrays of IACTs probe the very-high-energy gamma-ray sky. Their working principle consists of the simultaneous observation of air showers initiated by the interaction of very-high-energy gamma rays and cosmic rays with the atmosphere. Cherenkov photons induced by a given shower are focused onto the camera plane of the telescopes in the array, producing a multi-stereoscopic record of the event. This image contains the longitudinal development of the air shower, together with its spatial, temporal, and calorimetric information. The properties of the originating very-high-energy particle (type, energy, and incoming direction) can be inferred from those images by reconstructing the full event using machine learning techniques. In this contribution, we present a purely deep-learning driven, full-event reconstruction of simulated, stereoscopic IACT events using CTLearn. CTLearn is a package that includes modules for loading and manipulating IACT data and for running deep learning models, using pixel-wise camera data as input. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0
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
Contributions from the Cherenkov Telescope Array (CTA) Consortium to the ICRC 2011
No full textThe Cherenkov Telescope Array (CTA) is a project for the construction of a next generation VHE gamma ray observatory with full sky coverage. Its aim is improving by about one order of magnitude the sensitivity of the existing installations, covering about 5 decades in energy (from few tens of GeV to above a hundred TeV) and having enhanced angular and energy resolutions. During 2010 the project became a truly global endeavour carried out by a consortium of about 750 collaborators from Europe, Asia, Africa and the North and South Americas. Also during 2010 the CTA project completed its Design Study phase and started a Preparatory Phase that is expected to extend for three years and should lead to the starting of the construction of CTA. An overview of the CTA Consortium activities project will be given
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