Santiago de Chile - International agreements have been signed: the largest and most powerful range of gamma-ray telescopes in the world, 10 times more sensitive than existing instruments, can now be built. The University of Siena participates in the project, which is called Cherenkov Telescope Array (CTA), since its foundation, through the research group led by Professor Riccardo Paoletti from the Department of Physical Sciences, Earth and the Environment, in collaboration with the National Institute of Nuclear Physics of Pisa. The Telescope Array Observatory organization is building the gamma ray observatory in two sites in Chile, in the Atacama desert, and in the Canaries, while the general coordination is in Bologna. The project includes telescopes of different classes, 23 meters in diameter from the main mirror, 12 meters medium and small from 4 meters, all in the technical-scientific validation phase of the prototypes.