The Cherenkov Telescope Array (CTA,
or Cherenkov Telescope Array Observatory, CTAO)
is a Cherenkov gamma-ray telescope under construction that will
consist of two arrays of ground-based telescopes
for observation of gamma rays in the range of 20 GeV to 300 TeV.
One array is to be on the Atacama Desert in Chile (99 dishes,
near Paranal Observatory) and the other in Roque de los Muchachos Observatory (ORM) in the
Canary Islands (19 dishes).
Their aim is to spot high-energy gamma-ray photons by observing the
Cherenkov radiation such photons trigger in the upper atmosphere.
The method is indirect, but offers a much larger collecting area
than is practical with a space mission, such a large area being
necessary to detect a reasonable number of such high-energy photons
because they are so rare.
The dishes are not all identical, different subsets covering different
bands:
Prototype dishes for the various bands are in operation.
Some are to be Schwarzschild-Couder Telescopes (SCTs),
for which a 9.7-meter prototype (pSCT) has been constructed.
An LST prototype, LST1, is in operation at ORM.