Cerro Tololo Inter-American Observatory (CTIO)
A complex of astronomical telescopes and instruments located 70 km east
of La Serena, Chile, at an altitude of about 2,200 m on Cerro Tololo mountain.
Founded in 1963 and part of the U.S. National Optical Astronomy Observatories,
its main instrument is the 4-meter Blanco Telescope, opened in 1976, that
is the southern twin of the 4-m instrument at Kitt
Peak National Observatory. On a peak 10 kilometers to the southeast
is the 8-meter Gemini South telescope.