Largest primary mirror

In terms of area, the Gran Telescopio Canarias is the largest primary mirror, with an effective aperture of 10.4 m (410 in). Also known as GranTeCan or GTC, it is based at the Roque de los Muchachos Observatory on the island of La Palma, in the Canary Islands, Spain. The William P. Hobby-Robert E. Eberly Telescope at McDonald Observatory University of Texas, USA, and the Southern Africa Large Telescope ("SALT") in Sutherland, South Africa, both have an effective aperture of 9.2 m. These two telescopes are only the largest in one dimension (they are 11 m x 9.8 m ovoid).