Our key task was to manufacture and deliver precise optical fiber bundles that connect the telescope’s focal plane to the 4MOST spectrographs. At the end of 2021, we supplied bundles containing more than 2,400 individual fibers, each capturing light from a single celestial object. The production followed strict specifications, with special attention to the accurate placement and bonding of fibers into fiber arrays (v-groove arrays) forming the “fiber-slit” for the spectrographs, while keeping mechanical stress on the fibers to a minimum. Equally important was the high polishing quality of the fiber end surfaces, enabling efficient light coupling from faint astronomical sources. These parameters are crucial for accurate spectral measurements that determine the chemical composition, velocity, distance, and age of observed objects. In addition to the 2,436 science fibers, SQS also produced three fiber cables for calibration illumination and twelve fiber cables used to guide the telescope on target.
After production and testing, the bundles were integrated into the 4MOST system in Germany and transported to the Paranal Observatory in Chile in May 2025. Installation and preparations for full operation are currently underway, with first on-sky testing scheduled for October 2025 and full scientific observations expected to start early in 2026.
Instead of gathering spectra from stars and galaxies one object at a time—which is slow, time-consuming, and limited in reach—4MOST will record over 2,400 spectra simultaneously in a single exposure, enabling the survey of millions of objects over its lifetime. Over five years, more than 30 million spectra are expected to be recorded, aiding research on the Milky Way’s evolution, identification of extreme objects, and preparation for future space missions.
SQS is proud to be part of this extraordinary European mission, contributing key components that support the advancement of science, technology, and international collaboration.
Sources and recommended links:
4MOST Project: www.4most.eu
Leibniz-Institut for Astrophysics Potsdam (AIP): www.aip.de
4MOST Materials on AIP Website: www.aip.de/en/research/projects/4most/4most-material/
