On June 22, 2021, AST3-3 telescope which conducted trial observations in Yunnan Province was checked and accepted by expert group from Purple Mountain Observatory, Nanjing Institute of Astronomical Optics & Technology (NIAOT), Yunnan Observatory, Tsinghua University, Nanjing Astronomical Instrument Co., Ltd. etc.

AST3-3 is the third of AST3 series telescopes, same as the AST3-1 and AST3-2, with equator structure, main mirror aperture of 680mm, effective aperture of 500mm and focal ratio 3.73.

It adopted improved Schmidt system with large field of view, short cube and extinction distortion as well as atmospheric dispersion correction mirror (ADC) at the front end of the camera which can compensate most of atmospheric dispersion. The ultimate goal of AST3-3 is to install in the Dome A area to conduct astronomical observation.

To fully validate performance and reliability of the telescope, AST3-3 will conduct commissioning and scientific observations at domestic stations before installing in Antarctic. Preliminary installation and commissioning of AST3-3 was completed on 3 February so that automatic observation in n an unattended mode was officially conducted on March 16, 2021.

Until late June, AST3-3 has obtained more than 12, 000 effective images with best FWHM less than 2.5 arcseconds, best limit magnitude above 20 in 60 second exposure. After 80 images in 60 second exposure overlay, limit magnitude can reach 22.5. 

AST3-3 observation targets are mainly the supernova template, gamma-ray burst afterglow, variable stars etc.
Supernova module observed currently covered 1/4 visible sky area, and afterglow of GRB210420B, GRB210504 and GRB210527 has been observed.