WST: The Wide Field Spectroscopic Telescope

The WST project aims to design and construct an innovative 10-metre class wide-field spectroscopic survey telescope (WST) in the southern hemisphere. It will feature the parallel operation of two cutting-edge instruments: a high-multiplex (30,000), large field-of-view (3 square degrees) multi-object spectrograph (MOS) operating in both low- and high-resolution modes, and a giant panoramic integral field spectrograph (IFS).



WST’s ambitious top-level requirements place it well ahead of all existing and planned facilities. In its first five years of operation, the MOS is expected to observe 300 million galaxies, 25 million stars at low resolution, and 2 million stars at high resolution, while the IFS will deliver 4 billion spectra. These capabilities will enable transformative science across a wide range of astrophysical domains.



A key strength of WST lies in the synergy between its MOS and IFS instruments, offering highly complementary spectroscopic survey modes. This dual approach is central to the project’s scientific ambition.



WST is envisioned as the next major facility for ESO following the ELT, and a proposal will be submitted in response to the upcoming ESO Call for Ideas in 2027. The project is backed by a large consortium of leading institutes from nine European countries and Australia, with deep expertise in astronomical instrumentation and survey science.