lasilla

La Silla Observatory, often referred to simply as La Silla, is an astronomical observatory located in northern Chile and operated by the European Southern Observatory (ESO). It sits in the southern Atacama Desert at an altitude of about 2,400 meters above sea level, near the town of La Serena in the Coquimbo Region. The site is chosen for its clear, dark skies, dry air, and stable atmospheric conditions favorable to optical astronomy.

La Silla was ESO’s first major site for ground-based astronomy and became a cornerstone of southern hemisphere observing facilities. The complex hosts several prominent telescopes and instruments, including the ESO 3.6-meter telescope, the New Technology Telescope (NTT) with active optics, and the 2.2-meter telescope. The 3.6-meter telescope is notable for housing the HARPS instrument, a high-precision spectrograph used extensively in exoplanet searches and radial velocity measurements. The 2.2-meter telescope carries the FEROS high-resolution spectrograph, among other instruments. The NTT pioneered the use of active optics on large telescopes and served as a technological precursor for later ESO designs. The observatory has also hosted versatile instruments such as EMMI (ESO Multi-Mode Instrument) on the NTT.

Research at La Silla covers a broad range of areas, including stellar astronomy, exoplanets, galactic and extragalactic studies, and time-domain investigations. Today, La Silla remains an active part of ESO’s network of southern observatories, complementing facilities at Paranal and other Chilean sites, and contributing to long-term surveys, targeted programs, and international collaborations. The site continues to support data releases and international access to its facilities for the scientific community.