From Large Telescopes to the MUltiplexed Survey Telescope (MUST)

TL;DR

The paper discusses the development of MUST, a next-generation wide-field, multiplexed spectroscopic telescope designed to significantly advance cosmology and astrophysics by enabling large-scale 3D mapping of the Universe.

Contribution

It introduces MUST, a 6.5-meter Stage-V spectroscopic telescope capable of simultaneous spectra for over 20,000 targets, addressing the need for advanced wide-field spectroscopic surveys.

Findings

MUST will obtain spectra for over 100 million galaxies and quasars.

It will provide the most comprehensive 3D map of the Universe to date.

MUST will open new avenues in cosmology, Galactic structure, and time-domain astrophysics.

Abstract

Recent advances in astronomical observations have ushered in an era of remarkable discoveries. We now probe the Universe through multi-messenger signals, image the sky with unprecedented depth and resolution, and investigate individual sources using powerful large-aperture telescopes. Yet, a critical gap persists: the lack of wide-field, highly multiplexed spectroscopic capabilities needed to fully exploit the wealth of imaging data from current and upcoming surveys. In this review, we trace the historical development of large optical telescopes and spectroscopic surveys, assess the capabilities of ongoing and near-future facilities, and motivate the need for next-generation Stage-V spectroscopic experiments. As a representative example, we present the MUltiplexed Survey Telescope (MUST), the first Stage-V spectroscopic facility currently under construction. MUST is a 6.5-meter telescope designed to obtain optical spectra for over 20,000 targets simultaneously within a $\sim$5 deg$^2$ field, using a modular focal plane populated with 6.2-mm pitch fiber-positioning robots. Over an 8-year survey in the 2030s, MUST aims to build the most comprehensive 3D spectroscopic map of the Universe to date, measuring redshifts for over 100 million galaxies and quasars and opening new windows into cosmology, Galactic structure, and time-domain astrophysics.