The CTAO (’Cherenkov Telescope Array Observatory’) array will be the next generation of Cherenkov telescopes, succeeding the HESS, MAGIC and VERITAS arrays operated by international collaborations. The phenomena studied by this array (supermassive black holes, etc.) will be among the most energetic in the universe. Compared with its predecessors, it will offer an order-of-magnitude gain in sensitivity, a broadening of the observable spectral range from a few tens of GeV to 300 TeV, and an improvement in angular resolution to around 2 arcminutes. CTAO is one of France’s "grandes infrastructures de recherche" (IR*) and is on the European ESFRI list.
The CTAO network will be made up of sub-networks of telescopes of different sizes: LSTs (’Large-Sized Telescopes’, whose primary mirror measures 23 m in diameter), MSTs (’Medium-Sized Telescopes’, whose primary mirror measures 12 m in diameter) and SSTs (’Small-Sized Telescopes’, whose primary mirror measures 4 m in diameter). Although these telescopes are distributed over two sites in the northern and southern hemispheres, the SSTs will only be installed in the southern hemisphere on the CTA-S site located in the Chilean Andes in the Atacama Desert, close to ESO’s VLT and future ELT sites.
A team from UNIDIA, in collaboration with a scientific team from LUX and with the support of CNRS, has been involved in SST development studies since 2011. These studies have led to the development and construction on the Meudon site of a prototype Cherenkov telescope (pGCT), whose two-mirror optical concept is based on the Schwarzschild-Couder concept. Since 2021, UNIDIA and LUX have represented Observatoire de Paris - PSL and CNRS in the international CTA-SST consortium. This consortium, led by INAF, aims to provide, as an in-kind contribution, 37 SSTs in alpha configuration to CTAO. UNIDIA’s know-how is being put to good use in this project, as its technical team is positioned in project management, product assurance and RAMS manager, system engineer and AIT/V engineer roles, and has also been involved in mechanical developments. UNIDIA’s design office optimized the telescope’s Dish M1, the master structure that supports the entire optical structure (M1 and M2 mirrors, camera), using a method based on topological optimization tools. Production of the telescopes financed by France will start at the end of 2025, with delivery to the CTA-S site scheduled between 2026 and 2028. These activities will be carried out by an industrial company selected following a call for tenders, launched at the end of 2024 with the support of the CNRS.
Optimization of the Dish M1 on the CTA-SST telescope. (left): CAD rear view of the mechanical structure and (right) Gravity-induced displacements calculated by finite element analysis when the telescope is pointing at the horizon.
More information : https://www.ctao.org/
