Abstract

Invited Talk - Splinter 4MOST   (MW-0337)

4MOST Facility Overview

Roelof S. de Jong; C. Jakob Walcher
Leibniz-Institut für Astrophysik Potsdam (AIP)

We present the first results from the 4-metre Multi-Object Spectroscopic Telescope (4MOST) facility, a new world-leading high-multiplex spectroscopic survey facility installed on ESO's VISTA telescope at Cerro Paranal Observatory in Chile. The instrument provides a 2.6°-diameter field-of-view in which 2,436 spectra are obtained simultaneously: 1,624 spectra of medium-resolution (R~6500) and wavelength coverage from 370–950nm in parallel with 812 spectra at high-resolution (R~20,000) in three wavelength bands. The instrument saw first light in October 2025 and, after extensive commission and science verification phases, normal science operations is expected to start in August 2026. In the first 5 year observing period the project aims for the spectroscopic analysis of 20–25 million sources obtained with the medium-resolution spectrograph and of approximately 5 million objects using the high-resolution spectrograph, in particular to compliment satellite missions like Gaia, eROSITA, Euclid, and PLATO. We will present highlights from the 25 different science programmes scheduled to run in the first 5-year survey, with science cases running from stellar and Milky Way science to galaxies, AGN, dark matter and cosmology. Also, the data release schedule will be presented, with the first Data Release (DR0) scheduled for the early 2027.