The European Southern Observatory is an intergovernmental, European organisation for astronomical research. It has eight member countries: Belgium, Denmark, France, Germany, Italy, the Netherlands, Sweden and Switzerland.. ESO operates astronomical observatories in Chile and has its headquarters in Garching, near Munich, Germany.

ESO operates at two sites. It operates the La Silla observatory in the Atacama desert, 600 km north of Santiago de Chile, at 2,400 m altitude, where fourteen optical telescopes with diameters up to 3.6 m and a 15-m submillimetre radio telescope (SEST) are now in operation. In addition, ESO is in the process of building the Very Large Telescope (VLT) on Paranal, a 2,600 m high mountain approximately 130 km south of Antofagasta, in the driest part of the Atacama desert. The VLT consists of four 8.2-meter and several 1.8-meter telescopes. These telescopes can also be used in combination as a giant interferometer (VLTI). "First Light" of the first 8.2-meter telescope (UT1) occurred in May 1998. UT1 will be available on a regular basis for astronomical observations from April 1999 on. Over 1000 proposals are made each year for the use of the ESO telescopes.

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