A 10.4-m reflector with a mirror consisting of 36 hexagonal segments, opened in 2009 at an altitude of 2400 m at the Roque de los Muchachos Observatory, Canary Islands. It is jointly owned by Spain, Mexico, and the University of Florida, and is operated by the Instituto de Astrofísica de Canarias.
http://www.gtc.iac.es/ Official telescope website.