The Cherenkov Telescope Array (CTA) will be the next generation very-high-energy gamma-ray observatory. CTA is expected to provide substantial improvement in accuracy and sensitivity with respect to existing instruments thanks to a tenfold increase in the number of telescopes and their state-of-the-art design. Detailed Monte Carlo simulations are used to further optimise the number of telescopes and the array layout, and to estimate the observatory performance using updated models of the selected telescope designs. These studies are presented in this contribution for the two CTA stations located on the island of La Palma (Spain) and near Paranal (Chile) and for different operation and observation conditions.
The Cherenkov Telescope Array (CTA) is an international project for a next-generation ground-based gamma-ray observatory. CTA, conceived as an array of tens of imaging atmospheric Cherenkov telescopes, comprising small, medium and large-size telescopes, is aiming to improve on the sensitivity of current-generation experiments by an order of magnitude and provide energy coverage from 20 GeV to more than 300 TeV. In this study we explore how the medium-sized telescopes layout design and composition impacts the overall CTA performance by analyzing Monte Carlo simulations including Davies-Cotton a…
The Cherenkov Telescope Array (CTA) will be the next generation of ground-based instrument for Very High Energy gamma-ray astronomy. It will improve the sensitivity of current telescopes by up to an order of magnitude and provide energy coverage from 20 GeV up to 300 TeV. This improvement will be achieved using a total of 19 and 99 telescopes of three different sizes spread out over 0.4 and 4.5 km$^2$ at two sites, respectively, in the Northern and Southern Hemispheres. After a concerted effort involving three different large-scale Monte Carlo productions performed during the last years, here,…
Kilometric-scale optical imagers seem feasible to realize by intensity interferometry, using telescopes primarily erected for measuring Cherenkov light induced by gamma rays. Planned arrays envision 50--100 telescopes, distributed over some 1--4 km$^2$. Although array layouts and telescope sizes will primarily be chosen for gamma-ray observations, also their interferometric performance may be optimized. Observations of stellar objects were numerically simulated for different array geometries, yielding signal-to-noise ratios for different Fourier components of the source images in the interfero…
Reconstruction of energies of very-high-energy gamma-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 tel…
The Cherenkov Telescope Array is the next generation ground-based observatory for the study of very-high-energy gamma-rays. It will provide an order of magnitude more sensitivity and greater angular resolution than present systems as well as an increased energy range (20 GeV to 300 TeV). For the high energy portion of this range, a relatively large area has to be covered by the array. For this, the construction of ~7 m diameter Cherenkov telescopes is an option under study. We have proposed an innovative design of a Davies-Cotton mount for such a telescope, within Cherenkov Telescope Array spe…
The Yakutsk array group is developing a wide field-of-view Cherenkov telescope to be operated in coincidence with the surface detectors of the extensive air shower array. Currently, the engineering prototype of the reflecting telescope with the front-end electronics is designed, assembled, and tested to demonstrate the feasibility of the conceived instrument. The status and specifications of the prototype telescope are presented, as well as the modernization program of the already existing Cherenkov light detectors subset of the array measuring ultra-high energy cosmic rays.
A medium-sized Schwarzchild-Couder Telescope (SCT) is being developed as a possible extension for the Cherenkov Telescope Array (CTA). The Cherenkov camera of the telescope is designed to have 11328 silicon photomultiplier pixels capable of capturing high-resolution images of air showers in the atmosphere. The combination of the large number of pixels and the high trigger rate (> 5 kHz) expected for this telescope results in a multi-Gbps data throughput. This sets challenging requirements on the design and performance of a data acquisition system for processing and storing this data. A prototy…
We analyze temporal characteristics of signals from the wide field-of-view (WFOV) Cherenkov telescope (CT) detecting extensive air showers (EAS) of cosmic rays (CR) in coincidence with surface detectors of the Yakutsk array. Our aim is to reveal causal relationships between measured characteristics and physical properties of EAS.
The Cherenkov Telescope Array (CTA) is the next ground-based $γ$-ray observatory in the TeV $γ$-ray spectral region operating with the Imaging Atmospheric Cherenkov Technique. It is based on almost 70 telescopes of different class diameters - LST, MST and SST of 23, 12, and 4 m, respectively - to be installed in two sites in the two hemispheres (at La Palma, Canary Islands, and near Paranal, Chile). Several thousands of reflecting mirror tiles larger than 1 m$^2$ will be produced for realizing the segmented primary mirrors of a so large number of telescopes. Almost in parallel, the ASTRI Mini-…
A Central Laser Facility is a system composed of a laser placed at a certain distance from a light-detector array, emitting fast light pulses, typically in the vertical direction, with the aim to calibrate that array. During calibration runs, all detectors are pointed towards the same portion of the laser beam at a given altitude. Central Laser Facilities are used for various currently operating ultra-high-energy cosmic ray and imaging atmospheric Cherenkov telescope arrays. In view of the future Cherenkov Telescope Array, a similar device could provide a fast calibration of the whole installa…
The accurate measurement of the Cosmic Ray (CR) nuclear composition around and above the Knee (~ 10^15.5 eV) has been difficult due to uncertainties inherent to the measurement techniques and/or dependence on hadronic Monte Carlo simulation models required to interpret the data. Measurement of the Cherenkov air shower signal, calibrated with air fluorescence measurements, offers a methodology to provide an accurate measurement of the nuclear composition evolution over a large energy range. NICHE will use an array of widely-spaced, non-imaging Cherenkov counters to measure the amplitude and tim…
We compared convolutional neural networks to the classical boosted decision trees for the separation of atmospheric particle showers generated by gamma rays from the particle-induced background. We conduct the comparison of the two techniques applied to simulated observation data from the Cherenkov Telescope Array. We then looked at the Receiver Operating Characteristics (ROC) curves produced by the two approaches and discuss the similarities and differences between both. We found that neural networks overperformed classical techniques under specific conditions.
The Cherenkov Telescope Array (CTA) is an international next-generation ground-based gamma-ray observatory. CTA will be implemented as southern and northern hemisphere arrays of tens of small, medium and large-sized imaging Cherenkov telescopes with the goal of improving the sensitivity over the current-generation experiments by an order of magnitude. CTA will provide energy coverage from ~20 GeV to more than 300 TeV. The Schwarzschild-Couder (SC) medium size (9.5m) telescopes will feature a novel aplanatic two-mirror optical design capable of accommodating a wide field-of-view with significan…
The Cherenkov Telescope Array (CTA) will be the next generation observatory employing different types of Cherenkov telescopes for the detection of particle showers initiated by very-high-energy gamma rays. A good knowledge of the Earth's atmosphere, which acts as a calorimeter in the detection technique, will be crucial for calibration in CTA. Variations of the atmosphere's transparency to Cherenkov light and not correctly performed calibration of individual telescopes in the array result in large systematic uncertainties on the energy scale. The Cherenkov Transparency Coefficient (CTC), devel…
The VERITAS Cherenkov telescope array has been fully operational since Fall 2007 and has fulfilled or outperformed its design specifications. We are preparing an upgrade program with the goal to lower the energy threshold and improve the sensitivity of VERITAS at all accessible energies. In the baseline program of the upgrade we will relocate one of the four telescopes, replace the photo-sensors by higher efficiency photomultipliers and install a new trigger system. In the enhanced program of the upgrade we foresee, in addition, the construction of a fifth telescope and installation of an acti…
The upcoming Cherenkov Telescope Array (CTA) project is expected to provide unprecedented sensitivity in the low-energy ( <~100 GeV) range for Cherenkov telescopes. In order to exploit fully the potential of the telescopes the standard analysis methods for gamma/hadron separation might need to be revised. We study the composition of the background by identifying events composed mostly of a single electromagnetic subcascade or double subcascade from a π0 (or another neutral meson) decay. We apply the standard simulation and analysis chain of CTA to evaluate the potential of the standard analysi…
NectarCAM is a camera developed to detect Cherenkov light between 80 GeV and 30 TeV. It will equip the medium-sized telescopes (MST) of the Cherenkov Telescope Array Observatory (CTAO). The camera comprises 265 modules, covering a field of view of 8 degrees. Each module consists of 7 photomultiplier Tubes (PMTs) equipped with light guides and a front-end board performing the data capture. NectarCAM is based on the NECTAr chip, which combines a switch capacitor array sampling at 1GHz and a 12-bit Analog to Digital Converter (ADC). The NectarCAM camera is currently under integration in CEA Paris…
The aim of the Yakutsk array enhancement project is to create an instrument to study the highest-energy galactic cosmic rays (CRs) -- their sources, energy spectrum, and mass composition. Additionally, there will be unique capabilities for investigations in the transition region between galactic and extragalactic components of CRs. Using the well-developed imaging atmospheric Cherenkov telescope technique adapted to the energy region $E>10^{15}$ eV, we plan to measure the longitudinal structure parameters of the shower, e.g., angular and temporal distributions of the Cherenkov signal related t…
The Cherenkov Telescope Array (CTA) will be the world's largest and by far most sensitive observatory for high-energy gamma rays. It will be capable of detecting gamma rays from extremely faint sources with unprecedented precision on energy and direction in the energy range from 20 GeV to more than 300 TeV. The performance of the future CTA observatory derived from detailed Monte Carlo simulations is presented in this contribution for the two CTA sites in Paranal (Chile) and on the La Palma island (Spain).
The Cherenkov Telescope Array (CTA) is a next-generation ground-based observatory for g -rays with energies between some ten GeV and a few hundred TeV. CTA is currently in the advanced design phase and will consist of arrays with different size of prime-focus Cherenkov telescopes, to ensure a proper energy coverage from the threshold up to the highest energies. The extension of the CTA array with double-mirror Schwarzschild- Couder telescopes is planned to improve the array angular resolution over wider field of view.We present an end-to-end Monte-Carlo comparison of trigger concepts for the d…
For reliable event reconstruction of Imaging Atmospheric Cherenkov Telescopes (IACTs), calibration of the optical throughput efficiency is required. Within current facilities, this is achieved through the use of ring shaped images generated by muons. Here, a complementary approach is explored, achieving cross calibration of elements of IACT arrays through pairwise comparisons between telescopes, focussing on its applicability to the upcoming Cherenkov Telescope Array (CTA). Intercalibration of telescopes of a particular type using eventwise comparisons of shower image amplitudes has previously…
The Cherenkov Telescope Array (CTA) is the next generation very-high energy gamma-ray air-shower Cherenkov observatory. CTA will consist of many segmented-mirror telescopes of three different diameters, placed in two arrays, one in the Northern hemisphere and one in the South, thus covering the whole sky. The total number of mirror tiles will be of the order of 10000, corresponding to a reflective area of ~10^4 m^2. The Institute for Astronomy and Astrophysics in Tübingen is developing procedures to coat glass-substrate-based mirror tiles, is participating to the CTA mirror prototype testing, …
The Cherenkov Telescope Array (CTA) is planned to be the next-generation very-high-energy (VHE; E > 100 GeV) gamma-ray observatory. It is anticipated that CTA will improve upon the sensitivity of the current generation of VHE experiments, such as VERITAS, HESS and MAGIC, by an order of magnitude. CTA is planned to consist of two graded arrays of Cherenkov telescopes with three primary-mirror sizes. A proof-of-concept telescope, based on the dual-mirror Schwarzchild-Couder design, is being constructed on the VERITAS site at the F.L. Whipple Observatory in southern Arizona, USA, and is a candida…
Gamma-ray observations in the very-high-energy domain (E > 30 GeV) can exploit the imaging of few-nanosecond Cherenkov flashes from atmospheric particle showers. Photomultipliers have been used as the primary photosensors to detect gamma-ray induced Cherenkov light for the past 25 years, but they are increasingly challenged by the swift progress of silicon photomultipliers (SiPMs). We are working to identify the optimal photosensors for medium-sized Schwarzschild-Couder telescopes (SCT), which are proposed to contribute a significant fraction of the sensitivity of the Cherenkov Telescope Array…
The Cherenkov Telescope Array (CTA) represents the next generation of ground-based instruments for very-high-energy (VHE) gamma-ray astronomy, aimed at improving on the sensitivity of current-generation experiments by an order of magnitude and providing coverage over four decades of energy. The current CTA design consists of two arrays of tens of imaging atmospheric Cherenkov telescopes, comprising Small, Medium and Large-Sized Telescopes, with one array located in each of the Northern and Southern Hemispheres. To study the effect of the site choice on the overall \gls{cta} performance and sup…
Aiming to observe cosmic gamma rays in the 10 - 1000 TeV energy region, we propose a 10000 m^2 underground water-Cherenkov muon-detector (MD) array that operates in conjunction with the Tibet air-shower (AS) array. Significant improvement is expected in the sensitivity of the Tibet AS array towards celestial gamma-ray signals above 10 TeV by utilizing the fact that gamma-ray-induced air showers contain far fewer muons compared with cosmic-ray-induced ones. We carried out detailed Monte Carlo simulations to assess the attainable sensitivity of the Tibet AS+MD array towards celestial TeV gamma-r…
A Central Laser Facility is a system often used in astroparticle experiments based on arrays of fluorescence or Cherenkov light detectors. The instrument is based on a laser source positioned at a certain distance from the array, emitting fast light pulses in the vertical direction with the aim of calibrating the array and/or measuring the atmospheric transmission. In view of the future Cherenkov Telescope Array (CTA), a similar device could provide a calibration of the whole installation, both relative, i.e. each individual telescope with respect to the rest of the array, and absolute, with a…
The design of the camera support structures for the Cherenkov Telescope Array (CTA) Large Size Telescopes (LSTs) is based on an elliptical arch geometry reinforced along its orthogonal projection by two symmetric sets of stabilizing ropes. The main requirements in terms of minimal camera displacement, minimal weight, minimal shadowing on the telescope mirror, maximal strength of the structures and fast dynamical stabilization have led to the application of Carbon Fibre Plastic Reinforced (CFPR) technologies. This work presents the design, static and dynamic performance of the telescope fulfill…
The Cherenkov Telescope Array (CTA) Project will consist of two arrays of atmospheric Cherenkov telescopes to study high-energy gamma radiation in the range of a few tens of GeV to beyond 100 TeV. To achieve full-sky coverage, the construction of one array in each terrestrial hemisphere is considered. Suitable candidate sites are being explored and characterized. The candidate sites in the Southern Hemisphere include two locations in Argentina, one in San Antonio de los Cobres (Salta Province, Lat. 24:02:42 S, Long. 66:14:06 W, at 3600 m.a.s.l) and another one in El Leoncito (San Juan Province…
Co-sited with TA/TALE, the Non-Imaging CHErenkov Array (NICHE) will measure the flux and nuclear composition of cosmic rays from below 10^16 eV to 10^18 eV in its initial deployment. Furthermore, the low-energy threshold can be significantly decreased below the cosmic ray knee via counter redeployment or by including additional counters. NICHE uses easily deployable detectors to measure the amplitude and time-spread of the air-shower Cherenkov signal to achieve an event-by-event measurement of Xmax and energy, each with excellent resolution. NICHE will have sufficient area and angular acceptan…
It is anticipated that the forthcoming Cherenkov Telescope Array (CTA) will include a number of medium-sized telescopes that are constructed using a dual-mirror Schwarzschild-Couder configuration. These telescopes will sample a wide ($8^{\circ}$) field of view using a densely pixelated camera comprising over $10^{4}$ individual readout channels. A readout frequency congruent with the expected single-telescope trigger rates would result in substantial data rates. To ameliorate these data rates, a novel, hardware-level Distributed Intelligent Array Trigger (DIAT) is envisioned. A copy of the DIA…
The Cherenkov Telescope Array (CTA) is expected to become the by far largest and most sensitive observatory for very-high-energy gamma rays in the energy range from 20 GeV to more than 300 TeV. CTA will be capable of detecting gamma rays from extremely faint sources with unprecedented precision on energy and direction. The performance of the future observatory derived from detailed Monte Carlo simulations is presented in this contribution for the two CTA sites located on the island of La Palma (Spain) and near Paranal (Chile). This includes the evaluation of CTA sensitivity over observations p…
We present the development of a novel 11328 pixel silicon photomultiplier (SiPM) camera for use with a ground-based Cherenkov telescope with Schwarzschild-Couder optics as a possible medium-sized telescope for the Cherenkov Telescope Array (CTA). The finely pixelated camera samples air-shower images with more than twice the optical resolution of cameras that are used in current Cherenkov telescopes. Advantages of the higher resolution will be a better event reconstruction yielding improved background suppression and angular resolution of the reconstructed gamma-ray events, which is crucial in …
The Cherenkov Telescope Array will provide unprecedented sensitivity and angular resolution to gamma rays across orders of magnitude in energy. Above 1 TeV up to around 300 TeV an array of Small-Sized Telescopes (SSTs) will cover several kilometres on the ground. The Compact High-Energy Camera (CHEC) is a proposed option for the camera of the SSTs. CHEC contains 2048 pixels of physical size about 6 mm x 6 mm, leading to a field of view of over 8 degrees. Electronics based on custom ASICs (TARGET) and FPGAs sample incoming signals at a gigasample per second and provide a flexible triggering sch…
The Cherenkov Telescope Array (CTA) is a ground-based $γ$-ray observatory that will observe the full sky in the energy range from 20 GeV to 100 TeV from facilities in both hemispheres. It is proposed to consist of more than 100 telescopes, producing large amounts of data. Apart from the storage system, there are also requirements on the software framework to allow efficient data processing, i.e. robustness, execution speed and coding efficiency. This contribution will present a plain and simple pipeline framework design prototype for CTA that builds upon well-known tools, allowing the users to…
The Cherenkov Telescope Array (CTA) represents the next generation of ground based instruments for Very High Energy gamma-ray astronomy. It is expected to improve on the sensitivity of current instruments by an order of magnitude and provide energy coverage from 20 GeV to more than 200 TeV. In order to achieve these ambitious goals Monte Carlo (MC) simulations play a crucial role, guiding the design of CTA. Here, results of the second large-scale MC production are reported, providing a realistic estimation of feasible array candidates for both Northern and Sourthern Hemisphere sites performanc…
The Imaging Atmospheric Cherenkov Technique (IACT) is unusual in astronomy as the atmosphere actually forms an intrinsic part of the detector system, with telescopes indirectly detecting very high energy particles by the generation and transport of Cherenkov photons deep within the atmosphere. This means that accurate measurement, characterisation and monitoring of the atmosphere is at the very heart of successfully operating an IACT system. The Cherenkov Telescope Array (CTA) will be the next generation IACT observatory with an ambitious aim to improve the sensitivity of an order of magnitude…
We have developed an application-specific integrated circui (ASIC) for photomultipler tube (PMT) waveform digitization which is well-suited for the Schwarzschild-Couder optical system under development for the Cherenkov Telescope Array (CTA) project. The key feature of the "TARGET" ASIC is the ability to read 16 channels in parallel at a sampling speed of 1 GSa/s or faster. In combination with a focal plane instrumented with 64-channel multi-anode PMTs (MAPMTs), TARGET digitizers will enable CTA to achieve a wider field of view than the current Cherenkov telescopes and significantly reduce the…
The landscape of ground-based gamma-ray astronomy is drastically changing with the perspective of the Cherenkov Telescope Array (CTA) composed of more than 100 Cherenkov telescopes. For the first time in this energy domain, CTA will be operated as an observatory open to the astronomy community. In this context, a structured high level data model is being developed to describe a CTA observation. The data model includes different classes of metadata on the project definition, the configuration of the instrument, the ambient conditions, the data acquisition and the data processing. This last part…
Telescopes based on the imaging atmospheric Cherenkov technique (IACTs) detect images of the atmospheric showers generated by gamma rays and cosmic rays as they are absorbed by the atmosphere. The much more frequent cosmic-ray events form the main background when looking for gamma-ray sources, and therefore IACT sensitivity is significantly driven by the capability to distinguish between these two types of events. Supervised learning algorithms, like random forests and boosted decision trees, have been shown to effectively classify IACT events. In this contribution we present results from expl…
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…
For the proposed Cherenkov Telescope Array (CTA), a post-calibration point-source location accuracy of 3 seconds of arc is aimed for under favorable observing conditions and for gamma-ray energies exceeding 100 GeV. In this contribution, results of first studies on the location accuracy are presented. These studies are based on a toy Monte Carlo simulation of a typical CTA-South array layout, taking into account the expected trigger rates of the different CTA telescope types and the gamma-ray spectrum of the simulated source. With this simulation code it is possible to study the location accur…
The Cherenkov Telescope Array (CTA), a ground-based facility for very-high-energy (VHE) gamma-ray astronomy, will operate as an open observatory, serving a wide scientific community to explore and to study the non-thermal universe. Open community access is a novelty in this domain, putting a challenge on the implementation of services that make VHE gamma-ray astronomy as accessible as any other waveband. We present here the design of the CTA Observer Access system that comprises support of scientific users, dissemination of data and software, tools for scientific analysis, and the system to su…
The All Sky Camera (ASC) was developed as a universal device for the monitoring of the night sky quality. Eight ASCs are already installed and measure night sky parameters at eight of the candidate sites of the Cherenkov Telescope Array (CTA) gamma-ray observatory. The ACS system consists of an astronomical CCD camera, a fish eye lens, a control computer and associated electronics. The measurement is carried out during astronomical night. The images are automatically taken every 5 minutes and automatically processed using the control computer of the device. The analysis results are the cloud f…
The ASTRI Mini-Array is a project for the Cherenkov astronomy in the TeV energy range. ASTRI Mini-Array consists of nine Imaging Atmospheric Cherenkov telescopes located at the Teide Observatory (Canarias Islands). Large volumes of monitoring and logging data result from the operation of a large-scale astrophysical observatory. In the last few years, several "Big Data" technologies have been developed to deal with such volumes of data, especially in the Internet of Things (IoT) framework. We present the Monitoring, Logging, and Alarm (MLA) system for the ASTRI Mini-Array aimed at supporting th…
The Cherenkov Telescope Array (CTA), is an international project for the next generation ground- based observatory for gamma-ray astronomy in the energy range from 20 GeV to 300 TeV. The sensitivity in the core energy range will be dominated by up to 40 Medium-Sized Telescopes (MSTs). The MSTs, of Davies-Cotton type with a 12 m diameter reflector are currently in the prototype phase. A full-size mechanical telescope structure has been assembled in Berlin. The telescope is partially equipped with different mirror prototypes, which are currently being tested and evaluated for performances charac…
The Cherenkov Telescope Array (CTA) is the planned next-generation instrument for ground-based gamma-ray astronomy, covering a photon energy range of ~20 GeV to above 100 TeV. CTA will consist of the order of 100 telescopes of three sizes, installed at two sites in the Northern and Southern Hemisphere. This contribution deals with the 12 meter Medium Size Telescopes (MST) having a single mirror (modified Davies-Cotton, DC) design. In the baseline design of the CTA arrays, 25 MSTs in the South and 15 MSTs in the North provide the necessary sensitivity for CTA in the core energy range of 100 GeV…
The Cherenkov Telescope Array (CTA) will be the world's first observatory for detecting gamma-rays from astrophysical phenomena and is now in its prototyping phase with construction expected to begin in 2015/16. In this work we present the results from early attempts at detailed simulation studies performed to assess the need for atmospheric monitoring. This will include discussion of some lidar analysis methods with a view to determining a range resolved atmospheric transmission profile. We find that under increased aerosol density levels, simulated gamma-ray astronomy data is systematically …
The Cherenkov Telescope Array (CTA) will be the leading ground-base observatory for Very High Energy (VHE) γ-ray astronomy for the next decades. Its southern site will host about 70 Small Sized Telescopes (SSTs) which will determine the CTA sensitivity at γ-ray energies between 1 and 300 TeV. One of the design options for the SST cameras is the silicon photomultiplier-based Compact High-Energy Camera (CHEC-S). The back-end electronics (BEE) of CHEC-S interconnects the camera front-end modules, provides power and clock distribution, aggregation, routing and time stamping of data and most import…
This paper is concerned with the performance optimisation of an stereoscopic array of imaging atmospheric Cherenkov telescopes (IACTs) as a function of their positioning on the ground. In this first work we are concerned primarily with the study of the optimisation method and its test on toy arrays of few (3-6) telescopes. The ideas presented here were developed to investigate alternative ways of studying IACT array geometries. The proposal is an attempt to cover more exhaustively and systematically the parameter space involved in the design of a stereoscopic IACT array, aiming to develop a su…
The upcoming Cherenkov Telescope Array (CTA) project is expected to provide unprecedented sensitivity in the low-energy (<~100 GeV) range for Cherenkov telescopes. Most of the remaining background in this energy range results from misidentified hadron showers. In order to fully exploit the potential of the telescope systems it is worthwhile to look for ways to further improve the available analysis methods for γ/hadron separation. We study the composition of the background for the planned CTA-North array by identifying events composed mostly of a single electromagnetic subcascade or double sub…
The Spanish partners of the future Cherenkov Telescope Array (CTA) have selected a candidate site for the Northern installation of CTA, at 3 km from the Observatorio del Teide (OT), in the Canary Island of Tenerife. As the OT is a very well-characterized astronomical site. We focus here on differences between the publicly accessible measurements from the OT observatory and those obtained with instruments deployed at the candidate site. We find that the winds are generally softer at the candidate site, and the level of background light comparable to the Observatorio del Roque de los Muchachos (…
The Cherenkov Telescope Array (CTA) consortium aims to create the next generation Very High Energy gamma-ray observatory. It will be devoted to the observation of gamma rays over a wide band of energy, from 20 GeV to 300 TeV. Three different classes, Large, Medium and Small Size Telescopes, are foreseen to cover the low, intermediate and high energy regions, respectively. The energy range of the Small Size Telescopes (SSTs) extends from 1 TeV to 300 TeV. Among them, the Gamma-ray Cherenkov Telescope (GCT), a telescope based on a Schwarzschild-Couder dual-mirror optical design, is one of the pr…
The current generation of Cherenkov telescopes is mainly limited in their gamma-ray energy and flux reconstruction by uncertainties in the determination of atmospheric parameters. The Cherenkov Telescope Array (CTA) aims to provide high-precision data extending the duty cycle as much as possible. To reach this goal, it is necessary to continuously and precisely monitor the atmosphere by means of remote-sensing devices, which are able to provide altitude-resolved and wavelength-dependent extinction factors, sensitive up to the tropopause and higher. Raman LIDARs are currently the best suited te…
Two of the Key Science Projects of the Cherenkov Telescope Array (CTA) consist in performing a deep survey of the Galactic and Extragalactic sky, providing an unbiased view of the Universe at energies above tens of GeV. To optimize the time spent to perform the Extragalactic survey, a so-called "divergent mode" of the CTA was proposed as an alternative observation strategy to the traditional parallel pointing in order to increase its instantaneous field of view. The search for transient VHE sources would also benefit from an extended field of view. In the divergent mode, each telescope points …
The Gamma Cherenkov Telescope (GCT) is proposed to be part of the Small Size Telescope (SST) array of the Cherenkov Telescope Array (CTA). The GCT dual-mirror optical design allows the use of a compact camera of diameter roughly 0.4 m. The curved focal plane is equipped with 2048 pixels of ~0.2° angular size, resulting in a field of view of ~9°. The GCT camera is designed to record the flashes of Cherenkov light from electromagnetic cascades, which last only a few tens of nanoseconds. Modules based on custom ASICs provide the required fast electronics, facilitating sampling and digitisation as…
This contribution aims to introduce the single photo-electron system designed to calibrate the camera of the Medium-Sized Telescopes of the Cherenkov Telescope Array (CTA). This system will allow us to measure accurately the gain of the camera's photodetection chain and to constrain the systematic uncertainties on the energy reconstruction of gamma rays detected by CTA. The system consists of a white painted screen, a fishtail light guide, a flasher and an XY motorization to allow movement. The flashes guided by the fishtail mimic the Cherenkov radiation and illuminate the focal plane under th…
