The Cherenkov Telescope Array Observatory (CTAO) is the next-generation atmospheric Cherenkov gamma-ray project. CTAO will be deployed at two sites, one in the Northern and the other in the Southern Hemisphere, containing telescopes of three different sizes for covering different energy domains. The commissioning of the first CTAO Large-sized Telescope (LST-1) is being finalized at the CTAO Northern site. Additional calibration and environmental monitoring instruments such as laser imaging detection and ranging (LIDAR) instruments and weather stations will support the telescope operations. The Array Control and Data Acquisition (ACADA) system is the central element for onsite CTAO operations. ACADA controls, supervises, and handles the data generated by the telescopes and the auxiliary instruments. It will drive the efficient planning and execution of observations while handling the several Gb/s camera data generated by each CTAO telescope. The ACADA system contains the CTAO Science Alert Generation Pipeline – a real-time data processing and analysis pipeline, dedicated to the automatic generation of science alert candidates as data are being acquired. These science alerts, together with external alerts arriving from other scientific instruments, will be managed by the Transients Handler (TH) component. The TH informs the Short-term Scheduler of ACADA about interesting science alerts, enabling the modification of ongoing observations at sub-minute timescales. The capacity for such fast reactions – together with the fast movement of CTAO telescopes – makes CTAO an excellent instrument for studying high-impact astronomical transient phenomena. The ACADA software is based on the Alma Common Software (ACS) framework, and written in C++, Java, Python, and Javascript. The first release of the ACADA software, ACADA REL1, was finalized in July 2023, and integrated after a testing campaign with the LST-1 finalized in October 2023. This contribution describes the design and status of the ACADA software system.
The Cherenkov Telescope Array Observatory (CTAO) is the next-generation atmospheric Cherenkov gammaray Observatory. CTAO will be constructed on two sites, one array in the Northern and the other in the Southern hemisphere, containing telescopes of three different sizes, for covering different energy domains. To combine and orchestrate the different telescopes and auxiliary instruments (array elements), the Array Control and Data Acquisition (ACADA) system is the central element for the Observatory on-site operations: it controls, supervises, and handles the data generated by the array elements. Considering the criticality of the ACADA system for future Observatory operations, corresponding quality assurance provisions have been made at the different steps of the software development lifecycle, with focus on continuous integration and testing at all levels. To enable higher-level tests of the software deployed on a distributed system, an ACADA test cluster has been set up to facilitate testing and debugging of issues in a more realistic environment. Furthermore, a separate software integration and test cluster has also been established that allows for the off-site testing of the integrated software packages of ACADA and of the corresponding array elements. Here the software integration can be prepared, interfaces and interactions can be tested, and on-site procedures that are required later in the process can be checked beforehand, only limited by the simulation capabilities that are delivered as part of the software packages. Once preparations and testing with the off-site test cluster are completed, the integrated software can be deployed at the target site. The software packages and setup parameters are kept under configuration control at all stages, and deployment steps are documented to ensure that installations are reproducible. This methodology has been applied for the first time in the context of the integration of ACADA with the first CTAO Large-sized Telescope (LST-1) in October 2023.
KEYWORDS: Atmospheric Cherenkov telescopes, Control software, Software development, Telescopes, Observatories, Data acquisition, Astronomy, Lanthanum, Interfaces, Control systems
The Cherenkov Telescope Array Observatory (CTAO) is the next-generation ground-based instrument for gamma-ray astronomy. CTAO will be located at two sites, one in the Northern (La Palma, Spain) and the other in the Southern Hemisphere (Paranal, Chile), with telescopes in three different sizes to cover different energy ranges. The commissioning of the first CTAO Large-Sized Telescope (LST-1) is being finalized at the CTAO-North site. The Array Control and Data Acquisition (ACADA) software is a central element of on-site CTAO operations. ACADA comprises subsystems for central control, the short-term scheduler, monitoring systems, and data handling at rates of GB/s. Consequently, it is a very complex software that requires many developers with different expertise, such as control software, data acquisition, data analysis, scheduling, configuration, and human interfaces. To implement such complex software, ACADA has been broken down into subsystems, which CTAO delegates to expert developer teams around the world through in-kind contributions. All the software is under version control exploiting a dedicated installation of GitLab. We have created at least one repository for each subsystem and a final one for the integration. We have defined the software development and integration procedures so that all phases of the Software Development Life Cycle (SDLC) are supported. Particular attention has been paid to the critical time when a software version is in operation on site and, bug-fixing and new features need to be kept under version control in parallel. The goal is to manage bug fixes without adding new features out of the scope of the release, but at the same time to guarantee the distribution of bug fixes for future releases. This contribution presents our strategy to manage multiple software versions according to the CTAO development plan.
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