The Cherenkov Telescope Array (CTA) is a plan for a pair of arrays of ground-based telescopes on the Atacama Desert in Chile (99 dishes) and La Palma in the Canary Islands (19 dishes) for observation of Gamma Rays. Their aim is to spot high-energy gamma-ray photons by observing the Cherenkov Radiation they produce in the upper Atmosphere. The method is indirect, but offers a much larger collecting area than is practical with a space mission, which is what is needed for the photons of interest. The dishes are not identical, different sets covering different bands.
A prototype dish began operation in 2017.