Special Astrophysical Observatory (SAO)

The primary observing facility of the Russian Academy of Sciences for optical and radio astronomy. It is located in the Caucasus region between the Black Sea and the Caspian Sea. The optical observatory at Nizhnij Arkhyz near Zelenchukskaya is the location of the largest single-mirror optical telescope in the world, the Bolshoi Teleskop Azimutalnyi (Large Altazimuth Telescope), which has a 6-metre (236-inch) primary mirror. Completed in 1975, it was the very first large telescope to be designed on an altazimuth mounting. There are also a 1-metre (40-inch) -Ritchey-Chrétien telescope and a 60-cm (24-inch) Cassegrain reflector. The RATAN-600 radio telescope is located on the outskirts of Zelenchukskaya. There is also a radio branch of the SAO in St Petersburg.