170 inch (4.2 m) Reflector, La Palma

The home page for the William Herschel Telescope is : http://www.ing.iac.es/Astronomy/telescopes/wht/

The William Herschel Telescope (WHT) was the third largest single-mirror telescope in the world, when completed in July 1987. It was the last telescope made by Grubb Parsons before the company closed. It was the only telescope made by Grubbs to have an Altazimuth mount, the type of mount which is now seen on all of the world's great telescopes.