Xuntian

A planned 2 m off-axis telescope that will share the Tiangong space station's orbit and dock with it for servicing. Its survey camera, with a 1.1 deg²square degreeUnit of solid angle: one degree by one degree on the sky. The whole sky is about 41,253 deg²; the full Moon covers about 0.2 deg². field and 80% of the PSFpoint-spread functionThe image a system makes of a point source. Its width (often quoted as FWHM, or half-energy width for X-ray optics) sets the effective resolution; its shape matters for photometry, deblending and weak-lensing shape measurement. energy within 0.15″, will image about 17,500 deg² in seven bands from 255 to 1000 nm with slitless spectroscopyslitless spectroscopyPlacing a dispersing element (often a grism, a prism–grating combination) in the beam with no slit, so every source in the field gets a spectrum at once. Efficient for surveys; spectra of neighbours can overlap., for weak lensingweak gravitational lensingCoherent distortion of distant galaxy shapes, at the percent level, by mass along the line of sight. Averaged over millions of galaxies it maps dark matter and the growth of structure; it needs exquisite PSF control. and galaxy clustering on a scale comparable to Euclid.

Operator

CNSA, CAS

Orbit

Low Earth orbit, co-orbiting with Tiangong

Aperture

2 m

Passband

255 nm – 1000 nm

Launch

2027 (target)