Spotlight

The 2m-aperture Survey Space Telescope (also known as the China Space Station Telescope, CSST) is a major science project of the China Manned Space Program. It is expected to start science operations around 2024 and has a nominal mission lifetime of 10 years. During observations, CSST will fly independently in the same orbit as the space station while maintaining a large distance apart. It can dock with the space station for servicing as scheduled or as needed. With a Cook-type three-mirror anastigmat design, CSST can achieve superior image quality within a large field of view (FoV), which gives it an advantage for survey observations. The radius encircling 80% energy of its point spread function within the central 1.1 square degrees of FoV is required to be no more than 0.15”, including all wavefront errors in the optics and instruments and dynamical effects such as the telescope’s attitude control and vibration. CSST will be launched with 5 first-generation instruments including a Survey Camera, a Terahertz Receiver, a Multichannel Imager, an Integral Field Spectrograph, and a Cool Planet Imaging Coronagraph. The primary task of CSST is to carry out a high-resolution large-area multiband imaging and slitless spectroscopy survey covering the wavelength range of 255 nm to 1000 nm. It will take the Survey Camera roughly 7 years of operation accumulated over 10 years of orbital time to image roughly 17,500 square degrees of the sky in NUV, u, g, r, i, z, and y bands and take slitless spectroscopy of the same sky in 3 bands. The point-source 5σ limiting magnitudes in g and r bands can reach 26 (AB mag) or higher. The spectral resolution (R=λ/Δλ) of the slitless spectrograph is specified to be on average no less than 200, and the wide-band-equivalent limiting magnitudes in GV (400-620 nm) and GI (620-1000 nm) bands will reach 23 or higher. Deep fields will be selected for more observations to reach at least one magnitude deeper than the wide-area survey. I will give an update on the project and discuss its capabilities and survey performance.