Completion and early scientific observations of the ASTRI Mini-Array air Cherenkov experiment for ground-based gamma-ray astronomy

Abstract

The ASTRI Mini-Array is a next-generation ground-based gamma-ray experiment being built at the Observatorio del Teide (Tenerife, Canary Islands). It aims to explore the largely uncharted 1–200 TeV energy range with exceptional angular and spectral performance. The array includes nine identical 4-meter class imaging atmospheric Cherenkov telescopes (IACTs), each featuring the dual-mirror aplanatic Schwarzschild–Couder optical design and equipped with compact silicon photomultiplier (SiPM) cameras. These cameras use innovative peak-finder front-end electronics to provide a wide field of view (≥ 10° diameter) and high collection efficiency. During 2024–2025, the first ASTRI telescope completed its commissioning and started regular data collection, including a dedicated observation campaign of the Crab Nebula—the standard candle of very-high-energy gamma-ray astronomy—for about 200 hours with detection of the source under various observing conditions (zenith angles, moonlight levels, wobble-mode offsets). We report on the completion of the ASTRI Mini-Array, with all nine telescopes installed and some already equipped with focal-plane cameras. This enabled us to make the first observations in a stereoscopic configuration, demonstrating the design effectiveness and the system readiness for full-array operations. We outline the scientific potential of the ASTRI Mini-Array once fully operational: the broad field of view and excellent angular resolution will enable morphological and spectral studies of both point-like and extended gamma-ray sources (e.g., supernova remnants, pulsar wind nebulae, PeVatrons), monitor blazars at very high energies, follow up transient events, and investigate the origin of cosmic rays and hot topics in fundamental physics. The ASTRI Mini-Array aims to become one of the most sensitive instruments in the Northern Hemisphere at multi-TeV energies, bridging the observational gap between current IACTs and extensive air-shower arrays while offering unprecedented precision and versatility.