Optical system of the Three Antarctic Survey Telescopes

Dome A is the highest point on the Antarctic Plateau, and the Chinese Expedition Team first arrived here in 2005 January. It is an excellent site for astronomical observations. The first-generation Chinese Antarctic optical telescope CSTAR has been operating on Dome A since 2008 January. The second-generation Chinese telescopes known as the Three Antarctic Survey Telescopes (AST3) are currently being developed. AST3 includes three telescopes matched respectively with G-, R- and I-band filters. Each telescope is a catadioptric optical telescope with an entrance pupil diameter of 500 mm, an f-ratio of 3.73 and a field of view of 414. The optical system of the AST3 consists of a transparent aspherical plate, an aspherical primary mirror and a spherical refractive corrector with a filter before the focal plane. The main features of the AST3 are the following: good image quality, a planar focal plane, reduced atmospheric dispersion, an absence of distortion and a compact structure. The main scientific goal of the AST3 is to survey the sky. In 2012 January, the first telescope of the AST3 was successfully installed on Dome A.