Hale Telescope mirror.. It was completed in 1948 and is still in active use. The Hale Telescope represented the technological limit in building large optical telescopes for over 30 years. It was the largest telescope in the world until the Russian BTA-6 was built in 1976, and the second largest until the construction of the Keck Observatory Keck 1 in 1993. Hale supervised the building of the telescopes at the Mount Wilson Observatory with grants from the Carnegie Institution of Washington: the telescope in 1908 and the telescope in 1917. These telescopes were very successful, leading to the rapid advance in understanding
South African Astronomical Observatory moved to the Sutherland site. This telescope participates in the PLANET network. The 1.9m (74-inch) Radcliffe Telescope was commissioned for the Radcliffe Observatory in Pretoria where it was in use between 1948 and 1974. Following the closure of the Radcliffe Observatory it was moved to Sutherland where it became operational again in January 1976. Between 1951 and 2004 it was the largest telescope in South Africa. The telescope was manufactured by Sir Howard Grubb, Parsons and Co. This telescope was originally called the Automatic Photometric Telescope, but has been renamed the Alan Cousins Telescope in honour of Alan William James