Optical system of Jiao Tong University spectroscopic telescope (JUST)

Jiao Tong University Spectroscopic Telescope (JUST) is a 4.8-m wide-field spectroscopic telescope at the Lenghu site in Qinghai Province of China. The primary mirror of JUST adopts the latest segmented mirror active optics technology, which is composed of 18 hexagonal segments with a diameter of 1.1 meters each. JUST is a composite astronomical telescope that combines precision measurement of small target fields with spectral survey of large fields of view. The focal stations of JUST feature two Nasmyth foci, where three types of instruments are installed to conduct spectroscopic observations in order to explore the dark universe, trace the dynamic universe, and search for exoplanets. One station with a 10 arcmin field of view will be installed the high-resolution imaging and spectroscopic instruments, the other station featuring a wide-field and atmospheric dispersion corrector with a 1.2 degree field of view will be used for spectroscopic survey to search for stars and galaxies, etc. The wide-field Nasmyth focus will operate at wavelengths 0.35-1.3μm at the zenith distance of 0- 60°.The two Nasmyth foci can be switched by rotating the tertiary mirror .