Ground Observatories by Year of First Operation, 1871 to 2019

Founded on 24 October 1871 in Córdoba, Argentina, by President Domingo Faustino Sarmiento together with the American astronomer Benjamin Apthorp Gould. Gould began mapping the southern sky on the night of the inauguration, and his star atlas Uranometria Argentina recorded more than 7,000 stars.

Established in 1969 in Chile's Atacama Region by the Carnegie Institution for Science, which moved its primary research site here from Mount Wilson because of growing light pollution around Los Angeles. In 2017 its 1-meter Swope Telescope first identified the optical counterpart of the gravitational-wave source GW170817.

A German-Spanish observatory at 2,168 meters in the Sierra de Los Filabres in Andalusia, proposed in 1970 and officially opened in July 1975 with its 1.23-meter telescope. It now has four main telescopes, the largest being 3.5 meters.

In the Sacramento Mountains at Sunspot, New Mexico. Construction began in 1985 and full operations started in November 1994. The site hosts the 2.5-meter Sloan Foundation Telescope, used for the Sloan Digital Sky Survey since 2000, and the APOLLO lunar laser ranging experiment, which measures the Earth-Moon distance to millimeter precision.

A European Southern Observatory facility on Cerro Paranal in Chile, operating since 1998. In 2018 its GRAVITY and SINFONI instruments followed the star S2 past the Milky Way's central black hole and measured Schwarzschild orbital precession, a signature of general relativity, which capped Reinhard Genzel's 30-year campaign.

On Mount Graham in southeastern Arizona. It saw first light with a single mirror in October 2005 and became fully binocular by January 2008. Its two 8.4-meter mirrors collect as much light as an 11.8-meter telescope and, used interferometrically, resolve like a 22.8-meter one.

A 10-meter telescope at the Amundsen-Scott South Pole Station in Antarctica, with first light on 16 February 2007. It observes microwave to submillimeter wavelengths, aiming to measure the cosmic microwave background, and completed its first major survey of distant galaxy clusters in October 2011.

A 6-meter telescope on Cerro Toco in the Atacama Desert, built in 2007 to survey the cosmic microwave background, the relic radiation left by the Big Bang, at arcminute resolution. Its data was among the first to detect seven acoustic peaks in the background's power spectrum, and the Simons Observatory later succeeded it at the same site.

Opened on 12 June 2010 by Queen Beatrix of the Netherlands. Instead of dishes, it combines digitally the signals of thousands of simple antennas in stations across the Netherlands and partner countries, which makes it one of the largest radio telescopes ever built.

An array of 66 antennas on the high Chajnantor plateau in northern Chile, operating since 2013 at wavelengths from 3.6 to 0.32 millimeters. It took part in the Event Horizon Telescope project that produced the first direct image of a black hole.

Built from 2015 at the Dominion Radio Astrophysical Observatory in British Columbia, with science operations starting in late September 2018. It has no moving parts, uses four stationary cylindrical reflectors at 400 to 800 MHz, and observes half of the sky each day as the Earth turns.

Thirty-six identical 12-meter dishes at the CSIRO Murchison Radio-astronomy Observatory in Western Australia, built from 2009 and completed in 2019, when its major survey science projects started. It serves as a precursor to the international Square Kilometre Array and is used to detect fast radio bursts.