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
GREGOR Solar Telescope underway to implement multi-conjugate AO in 2014. GREGOR Solar Telescope GREGOR is a solar telescope, equipped with a 1.5 m primary mirror. located at the Teide Observatory on Tenerife in the Canary Islands. It replaces the older Gregory Coudé Telescope and was inaugurated on May 21, 2012. First light was on . GREGOR is the third-largest solar telescope in the world, after the Big Bear Observatory and the McMath-Pierce solar telescope. It is aimed at observing the solar photosphere and chromosphere at visible and infrared wavelengths. GREGOR sports a high-order adaptive optics (AO) system with a 256-actuator deformable mirrors and