Gran Telescopio Canarias telescope mirror. This telescope, also know as GTC or GranTeCan, is located on La Palma, the Canary Islands. The 10.4-metre mirror comprises 36 hexagonal segments with a active optics control system, working together as a reflective unit. The telescope has been the world's largest single-aperture optical telescope since it opened in 2009. Operated by institutions from Spain, the USA and Mexico, it is located at an altitude of 2267 metres at the Observatorio del Roque de los Muchachos. Photographed in 2019.