On 15 October 2026, the sub-array of four Large-Sized Telescopes (LSTs) that will operate at the Cherenkov Telescope Array Observatory ( CTAO ) site on the island of La Palma (CTAO-North) will be inaugurated. This infrastructure is driven by the CTAO LST Collaboration, the international consortium responsible for designing, building and operating these large-sized telescopes, a next-generation facility aimed at advancing very-high-energy gamma-ray astronomy and exploring the most extreme and violent phenomena in the universe.
The Institute of Cosmos Sciences of the University of Barcelona (ICCUB) has participated in the development of CTAO and in the conception of these four large telescopes. Four of its researchers, Josep Maria Paredes, Marc Ribó, David Gascón and Pol Bordas, have been involved in documenting the process, from the initial design phase through technological development and the scientific goals of the project.
The inauguration of the four telescopes marks a fundamental milestone in the development of CTAO, as it completes the construction of all the large-sized telescopes planned for CTAO-North. The first telescope, LST-1, was inaugurated in 2018 and has since been undergoing commissioning under the responsibility of the LST Collaboration. It is now joined by three additional large-sized telescopes, which will eventually be accompanied by medium-sized telescopes (MSTs).
However, this work does not end with this milestone. The LSTs must undergo an extensive commissioning phase carried out by the LST Collaboration before being formally accepted by the CTAO Central Organization (CTAO ERIC) and beginning operations and the exploitation of so-called "early science". LST-1 is expected to be the first telescope accepted, during 2027, bringing closer the start of the Observatory's major scientific output.
The design and construction of these telescopes has been carried out by the LST Collaboration, which has acted as an in-kind contributor to CTAO ERIC and has complied with strict technical requirements.
