La Silla

While Paranal is home to ESO’s flag-ship, the VLT, the original ESO observing site is on the mountain La Silla in the southern part of the Atacama desert, 600 km north of Santiago de Chile and at 2400 m altitude. Here, ESO operates several optical telescopes with mirror diameters of up to 3.6 metres.

The 3.5-m New Technology Telescope (NTT) was the first in the world to have a computer-controlled main mirror (active optics), a technology developed at ESO and now applied to the VLT and most of the world’s current large telescopes.

Elsewhere at La Silla, the ESO 3.6-m telescope has been in operation since 1977. Following major upgrades, it remains in the frontline among the 4-m-class telescopes in the southern hemisphere.

It is home to HARPS (High Accuracy Radial Velocity Planet Searcher), a spectrograph with unrivalled precision which is dedicated to the hunt for extrasolar planets.

The 2.2-m MPG/ESO Telescope opened in 1984, and is on indefinite loan to ESO from the Max Planck Gesellschaft. Its Wide Field Imager (WFI) camera has a field of view as large as the full Moon, enabling direct images and spectra to be taken of large areas of the sky.

Some more details about the operational instruments on La Silla is available on a separate page and via the Science Instrumentation page.

La Silla also hosts national telescopes, such as the 1.2-m Swiss Telescope and the 1.5-m Danish Telescope. These have been used in many scientific breakthroughs, including the discovery of the smallest exoplanet ever found, only five times the mass of the Earth.