THESEUS

THESEUS (for Transient High Energy Sky and Early Universe Surveyor) is a concept for a future ESA space observatory for recording transients including gamma-ray bursts (GRBs) and X-ray bursts, to be launched in the early 2030s. The THESEUS concept was a finalist for an ESA mission, but in 2021, an unrelated competing proposal was chosen instead. Instrument conception:

• SXI "Soft X-ray Imager" (for 0.3-5 keV).
• IRT "Infrared Telescope" (for 0.7-1.8 μm, for quick follow-up).
• XGIS "X-Gamma rays Imaging Spectrometer" (for 2 keV to 20 MeV).