La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several telescopes are located at the site and are partly maintained by ESO. The observatory is one of the largest in the Southern Hemisphere and was the first in Chile to be used by ESO.
The La Silla telescopes and instruments are located 150 km northeast of La Serena at the outskirts of the Chilean Atacama Desert, one of the driest and loneliest areas of the world. Like other observatories in this geographical area, La Silla is located far from sources of light pollution and, like the Paranal Observatory, home to the Very Large Telescope, it has one of the darkest night skies on the Earth.
La Silla’s transformation through time.
Following the decision in 1963 to approve Chile as the site for the ESO observatory, scouting parties were sent to various locations to assess their suitability. The site that was decided upon was La Silla in the southern part of the Atacama desert, 600 km north of Santiago de Chile and at an altitude of 2400 metres. Besides being government property, it had the added benefits of being in a dry, flat and easily accessible area, yet isolated and remote from any artificial light and dust sources. Originally named the Cinchado, it was renamed La Silla (the saddle in Spanish) after its saddle-like shape.
On October 30, 1964, the contracts were signed and an area of 245 square miles was purchased the following year. During 1965, temporary facilities were erected with living quarters, a workshop and storage area. The dedication ceremony of the road to the top took place in March 1966, two months after its completion. On 25 March 1969, the ESO site at La Silla was finally formally inaugurated by President Eduardo Frei Montalva. With a permanent base of dormitories, workshops, hotels and several functioning telescopes, the observatory was fully operational. The 1 m and 1.5 m telescopes had been erected in the late 1960s, and were joined in 1968 by the Gran Prismo Objectif telescope that had been previously been used in South Africa.
By 1976, the largest telescope planned, the 3.6 m, started operations. It was subsequently to have a 1.4m CAT (Coudé Auxiliary Telescope) attached.
In 1984, the 2.2m telescope began operations, while in March 1989, the 3.5 m New Technology Telescope (NTT) saw “first light”.
The program reaches its apex with the installation of the SEST in 1987 (Swedish ESO Submillimetre Telescope), the only large submillimetre telescope in the southern hemisphere, which was a combined project between ESO and the Swedish Natural Science Research Council.
During the end of the century some of the original telescopes were closed-the 1m Schmidt closed in 1998 and the 1.5m in 2002, whilst new equipment owned by various foreign observatories was introduced. A 1m telescope owned by Marseille Observatory opened in 1998, followed by a 1.2m telescope from Geneva Observatory in 2000.
ESO operates three major optical and near infrared telescopes at the La Silla site: the New Technology Telescope (NTT), the 3.6-m ESO Telescope, and the 2.2-m Max-Planck-ESO Telescope.
In addition La Silla hosts several other national and project telescopes: the 1.54-m Danish Telescope, the 1.2-m Leonhard Euler Telescope, the Rapid Eye Mount Telescope and the TAROT Telescope. These telescopes are not operated by ESO and hence do not fall under the responsibility of La Silla Science Operations.
The 2.2-metre Telescope has been in operation at La Silla since early 1984 and is on indefinite loan to ESO from the Max Planck Society (Max Planck Gesellschaft or MPG in German). Telescope time is shared between MPG and ESO observing programmes, while the operation and maintenance of the telescope are ESO’s responsibility.
The telescope hosts three instruments: the 67-million pixel Wide Field Imager with a field of view as large as the full Moon, which has taken many amazing images of celestial objects; GROND, the Gamma-Ray Burst Optical/Near-Infrared Detector, which chases the afterglows of the most powerful explosions in the Universe, known as gamma-ray bursts; and the high-resolution spectrograph, FEROS, used to make detailed studies of stars.