The Cherenkov Telescope Array (CTA) observatory will represent the new frontier of imaging atmospheric Cherenkov Telescope. The simultaneous use of large, medium and small telescopes (respectively LST, MST and SST) will allow to explore the astronomy related to the very high energy domain, typical of Gamma rays, with a sensitivity, angular resolution and image quality never seen before. Within this project, ASTRI, the Italian 2 mirrors Schwarzshild-Couder configuration Small SST led by Italian National Institute of Astronomy (INAF), has moved quickly developing a 4m class telescope prototype which has been tested with results which demonstrates excellent performance as well as wide margins for further improvements. On the basis of the experiences made on the prototype, this paper focus on the design enhancements carried out for the telescope which will be part of the Cherenkov Telescope Array.
ASTRI SST-2M is an imaging atmospheric Cherenkov telescope developed by the Italian National Institute of Astrophysics (INAF) in the framework of the Cherenkov Telescope Array (CTA) project as an end-to-end prototype for the Small Size array. Large-, medium-, and small-sized telescopes will compose the CTA observatory that represents the next generation of imaging atmospheric Cherenkov telescopes and will explore the very high-energy domain from a few tens of GeV up to few hundreds of TeV. The ASTRI SST-2M telescope has been installed at the INAF-Catania observing station at Serra La Nave, on Mt. Etna (Sicily, Italy) in September 2014. In these 3 years of open-air operations the telescope has been commissioned and its opto-mechanical performance is now well understood. The apparatus was made ready to host its main scientific instrument, the camera with Silicon-Photomultiplier based detectors. This contribution is a status report on the complete ASTRI SST-2M telescope assembly including the electro-mechanical structure and the optical system.
ASTRI is an on-going project developed in the framework of the Cherenkov Telescope Array (CTA). An end- to-end prototype of a dual-mirror small-size telescope (SST-2M) has been installed at the INAF observing station on Mt. Etna, Italy. The next step is the development of the ASTRI mini-array composed of nine ASTRI SST-2M telescopes proposed to be installed at the CTA southern site. The ASTRI mini-array is a collaborative and international effort carried on by Italy, Brazil and South-Africa and led by the Italian National Institute of Astrophysics, INAF. To control the ASTRI telescopes, a specific ASTRI Mini-Array Software System (MASS) was designed using a scalable and distributed architecture to monitor all the hardware devices for the telescopes. Using code generation we built automatically from the ASTRI Interface Control Documents a set of communication libraries and extensive Graphical User Interfaces that provide full access to the capabilities offered by the telescope hardware subsystems for testing and maintenance. Leveraging these generated libraries and components we then implemented a human designed, integrated, Engineering GUI for MASS to perform the verification of the whole prototype and test shared services such as the alarms, configurations, control systems, and scientific on-line outcomes. In our experience the use of code generation dramatically reduced the amount of effort in development, integration and testing of the more basic software components and resulted in a fast software release life cycle. This approach could be valuable for the whole CTA project, characterized by a large diversity of hardware components.
The ASTRI mini-array, composed of nine small-size dual mirror (SST-2M) telescopes, has been proposed to be installed at the southern site of the Cherenkov Telescope Array (CTA), as a set of preproduction units of the CTA observatory. The ASTRI mini-array is a collaborative and international effort carried out by Italy, Brazil and South Africa and led by the Italian National Institute of Astrophysics, INAF. We present the main features of the current implementation of the Mini-Array Software System (MASS) now in use for the activities of the ASTRI SST-2M telescope prototype located at the INAF observing station on Mt. Etna, Italy and the characteristics that make it a prototype for the CTA control software system. CTA Data Management (CTADATA) and CTA Array Control and Data Acquisition (CTA-ACTL) requirements and guidelines as well as the ASTRI use cases were considered in the MASS design, most of its features are derived from the Atacama Large Millimeter/sub-millimeter Array Control software. The MASS will provide a set of tools to manage all onsite operations of the ASTRI mini-array in order to perform the observations specified in the short term schedule (including monitoring and controlling all the hardware components of each telescope and calibration device), to analyze the acquired data online and to store/retrieve all the data products to/from the onsite repository.
ASTRI SST-2M is an end-to-end telescope prototype developed by the Italian National Institute of Astrophysics (INAF) in the framework of the Cherenkov Telescope Array (CTA). The CTA observatory, with a combination of large-, medium-, and small-sized telescopes (LST, MST and SST, respectively), will represent the next generation of imaging atmospheric Cherenkov telescopes. It will explore the very high-energy domain from a few tens of GeV up to few hundreds of TeV.
The ASTRI SST-2M telescope structure and mirrors have been installed at the INAF observing station at Serra La Nave, on Mt. Etna (Sicily, Italy) in September 2014. Its performance verification phase began in autumn 2015. Part of the scheduled activities foresees the study and characterization of the optical and opto-mechanical performance of the telescope prototype.
In this contribution we report the results achieved in terms of kinematic model analysis, mirrors reflectivity evolution, telescopes positioning, flexures and pointing model and the thermal behavior.
The ASTRI SST-2M telescope is an end-to-end prototype proposed for the Small Size class of Telescopes (SST) of the future Cherenkov Telescope Array (CTA). The prototype is installed in Italy at the INAF observing station located at Serra La Nave on Mount Etna (Sicily) and it was inaugurated in September 2014. This paper presents the software and hardware architecture and development of the system dedicated to the control of the mount, health, safety and monitoring systems of the ASTRI SST-2M telescope prototype. The mount control system installed on the ASTRI SST-2M telescope prototype makes use of standard and widely deployed industrial hardware and software. State of the art of the control and automation industries was selected in order to fulfill the mount related functional and safety requirements with assembly compactness, high reliability, and reduced maintenance. The software package was implemented with the Beckhoff TwinCAT version 3 environment for the software Programmable Logical Controller (PLC), while the control electronics have been chosen in order to maximize the homogeneity and the real time performance of the system. The integration with the high level controller (Telescope Control System) has been carried out by choosing the open platform communications Unified Architecture (UA) protocol, supporting rich data model while offering compatibility with the PLC platform. In this contribution we show how the ASTRI approach for the design and implementation of the mount control system has made the ASTRI SST-2M prototype a standalone intelligent machine, able to fulfill requirements and easy to be integrated in an array configuration such as the future ASTRI mini-array proposed to be installed at the southern site of the Cherenkov Telescope Array (CTA).
The Italian National Institute for Astrophysics (INAF) is leading the Astrofisica con Specchi a Tecnologia Replicante Italiana (ASTRI) project whose main purpose is the realization of small size telescopes (SST) for the Cherenkov Telescope Array (CTA). The first goal of the ASTRI project has been the development and operation of an innovative end-to-end telescope prototype using a dual-mirror optical configuration (SST-2M) equipped with a camera based on silicon photo-multipliers and very fast read-out electronics. The ASTRI SST-2M prototype has been installed in Italy at the INAF “M.G. Fracastoro” Astronomical Station located at Serra La Nave, on Mount Etna, Sicily. This prototype will be used to test several mechanical, optical, control hardware and software solutions which will be used in the ASTRI mini-array, comprising nine telescopes proposed to be placed at the CTA southern site. The ASTRI mini-array is a collaborative and international effort led by INAF and carried out by Italy, Brazil and South-Africa. We present here the use cases, through UML (Unified Modeling Language) diagrams and text details, that describe the functional requirements of the software that will manage the ASTRI SST-2M prototype, and the lessons learned thanks to these activities. We intend to adopt the same approach for the Mini Array Software System that will manage the ASTRI miniarray operations. Use cases are of importance for the whole software life cycle; in particular they provide valuable support to the validation and verification activities. Following the iterative development approach, which breaks down the software development into smaller chunks, we have analysed the requirements, developed, and then tested the code in repeated cycles. The use case technique allowed us to formalize the problem through user stories that describe how the user procedurally interacts with the software system. Through the use cases we improved the communication among team members, fostered common agreement about system requirements, defined the normal and alternative course of events, understood better the business process, and defined the system test to ensure that the delivered software works properly. We present a summary of the ASTRI SST-2M prototype use cases, and how the lessons learned can be exploited for the ASTRI mini-array proposed for the CTA Observatory.
The Cherenkov Telescope Array (CTA) observatory, with a combination of large-, medium-, and small-size telescopes (LST, MST and SST, respectively), will represent the next generation of imaging atmospheric Cherenkov telescopes. It will explore the very high-energy domain from a few tens of GeV up to few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging resolution.
In this framework, the Italian ASTRI program, led by the Italian National Institute of Astrophysics (INAF), is currently developing a scientific and technological SST dual-mirror end-to-end prototype named ASTRI SST-2M. It is a 4-meter class telescope; it adopts an aplanatic, wide-field, double-reflection optical layout in a Schwarzschild-Couder configuration. The ASTRI SST-2M telescope structure and mirrors have been already installed at the INAF observing station at Serra La Nave, on Mt. Etna (Sicily, Italy).
In this contribution we report about the on-site deployment and the latest results on the opto-mechanical performance test conducted soon after the telescope installation
ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is a flagship project of the Italian Ministry of Research and led by the Italian National Institute of Astrophysics (INAF). One of its aims is to develop, within the Cherenkov Telescope Array (CTA) framework, an end-to-end small-sized telescope prototype in a dual-mirror configuration (SST-2M) in order to investigate the energy range E ~ 1-100 TeV. A long-term goal of the ASTRI program is the production of an ASTRI/CTA mini-array composed of seven SST-2M telescopes. The prototype, named ASTRI SST-2M, is seen as a standalone system that needs only network and power connections to work. The software system that is being developed to control the prototype is the base for the Mini-Array Software System (MASS), which has the task to make possible the operation of both the ASTRI SST-2M prototype and the ASTRI/CTA mini-array. The scope of this contribution is to give an overview of the hardware and software architecture adopted for the ASTRI SST- 2M prototype, showing how to apply state of the art industrial technologies to telescope control and monitoring systems.
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