The European Southern Observatory's telescopes stand in Chile's Atacama Desert at Paranal, Cerro Armazones and Chajnantor

Background

The European Southern Observatory runs its observing facilities in the Atacama Desert of northern Chile. Paranal Observatory stands at 2635 metres above sea level and is the home of the Very Large Telescope. The Very Large Telescope has four Unit Telescopes with main mirrors of 8.2m diameter, named Antu, Kueyen, Melipal and Yepun, which can work together as the Very Large Telescope Interferometer. The Extremely Large Telescope is being built at Cerro Armazones, Atacama Desert, Chile, at an altitude of 3046 m, with a main mirror diameter of 39 metres made up of 798 segments. ALMA, the Atacama Large Millimeter/submillimeter Array, sits on the Chajnantor plateau at 5000 meters above sea level and comprises 66 high-precision antennas spread over distances of up to 16 kilometres. Signals at millimetre and submillimetre wavelengths are heavily absorbed by water vapour in the Earth's atmosphere, so telescopes for this kind of astronomy must be built on high, dry sites. NOIRLab separately operates the Cerro Tololo Inter-American Observatory at an altitude of 2200 meters, with the Víctor M. Blanco 4-meter Telescope, while the NSF–DOE Vera C. Rubin Observatory, whose 8.4-meter Simonyi Survey Telescope stands on Cerro Pachón, is operated by NOIRLab and SLAC together.