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Although celestial sources emitting in the few tens of GeV up to a few TeV are being investigated by imaging atmospheric Čerenkov telescope arrays such as H.E.S.S., MAGIC, and VERITAS, at higher energies, up to PeV, more suitable instrumentation is required to detect ultra-high-energy photons, such as extensive air shower arrays, as HAWC, LHAASO, Tibet AS- γ. The Italian National Institute for Astrophysics has recently become the leader of an international project, the ASTRI Mini-Array, with the aim of installing and operating an array of nine dual-mirror Čerenkov telescopes at the Observatorio del Teide in Spain starting in 2025. The ASTRI Mini-Array is expected to span a wide range of energies (1–200 TeV), with a large field of view (about 10 degrees) and an angular and energy resolution of ∼3 arcmin and ∼10 %, respectively. The first four years of operations will be dedicated to the exploitation of Core Science, with a small and selected number of pointings with the goal of addressing some of the fundamental questions on the origin of cosmic rays, cosmology, and fundamental physics, the time-domain astrophysics and non γ -ray studies (e.g., stellar intensity interferometry and direct measurements of cosmic rays). Subsequently, four more years will be dedicated to Observatory Science, open to the scientific community through the submission of observational proposals selected on a competitive basis. In this paper, I will review the Core Science topics and provide examples of possible Observatory Science cases, taking into account the synergies with current and upcoming observational facilities. [ABSTRACT FROM AUTHOR]

In this paper, the statistics of cloud cover at night from 2016 to 2018 above the Ali observatory has been summarized, using the meso-scale numerical model and the cameras (Canon and AllSky-340 Camera). Above the western Tibetan Plateau, in the area of 200 km × 200 km centred at the Ali site, the average cloud cover during night was basically less than 30 per cent in 2016, and the Ali site was located in the zone with small value around 20 per cent; large cloud cover always occurred in summer, with mean value above 50 per cent in most parts of this area; while in winter, the smallest cloud cover was basically below 10 per cent; in other seasons, the cloud cover was mostly less than 30 per cent, and the Ali site located in the zone with cloud cover below 10 per cent in autumn and below 20 per cent in spring. At each monitored field of view from 90° to 45°, the cloud cover varied little; the proportion of clear nights with cloud cover below 10 per cent was close to 60 per cent of total observable nights per year, and the less cloudy nights with cloud cover below 40 per cent accounted for more than 70 per cent, besides, the observable nights with cloud cover below 70 per cent was around 80 per cent every year. Generally, the cloud cover condition at the Ali observatory above the western plateau is excellent, there are always abundant observable nights, while a bit worse just in July and August. Meanwhile, the numerical model has been proved to be a reliable tool to estimate cloud cover conditions above the Tibetan Plateau. [ABSTRACT FROM AUTHOR]