Victor Blanco four-metre telescope inside its protective dome at the Cerro Tololo Inter-American Observatory (CTIO) near La Serena, Chile, with other telescope domes in the background. The telescope makes observations at optical & infrared wavelengths. It is one of the largest telescopes in the southern hemisphere and can detect objects 6 million times fainter than those visible to the naked eye. It is housed inside a circular building which is 38m high & 33m wide. This instrument was completed in 1975 and is a twin to the four-metre Mayall telescope at Kitt Peak Observatory in Arizona, USA. In 1997 the CTIO is operated by the National Optical Astronomy Observatories (NOAO).