Construction agreement for the MOSAIC instrument on ESO's Extremely Large Telescope signed
On Monday 1st of December, the European Southern Observatories (ESO) has signed an agreement with a large international consortium for the design and construction of the Multi-Object Spectrograph (MOSAIC), an instrument for ESO’s Extremely Large Telescope (ELT). Able to measure the light from more than two hundred sources at the same time, MOSAIC will be used to trace the growth of galaxies and the distribution of matter from the Big Bang to the present day. Astronomers from Stockholm University are involved in both construction of the instrument, and the scientific exploration that will be done with it.
Artist's impression of MOSAIC at ELT. Credit: ESO.
MOSAIC is a powerful spectrograph: an instrument that splits light into its component wavelengths so astronomers can determine important properties of astronomical objects, such as their chemical composition or temperature. The instrument will use the widest possible field of view provided by the ELT, operating in both visible and near-infrared light, and will be able to analyse the light for more than two hundred objects simultaneously.
MOSAIC will conduct the first exhaustive inventory of matter in the early Universe, lifting the veil on how matter is distributed within and between galaxies and greatly advancing our understanding of how present-day galaxies formed and evolved. It will also be able to take a close look at the gas surrounding galaxies and identify the chemical elements within it.
The MOSAIC project team (Roser Pello, Mathieu Puech, Myriam Rodrigues, Hermine Schnetler, Patrick Caillier, Alessandro Meoli, Oliver Pfuhl, Cyrielle Blanc) at the signing ceremony. Alain Schuhl (Deputy Chief Executive Officer for Science, CNRS) and Xavier Barcons (Director General, ESO) are in the foreground. Photo: ESO.
The agreement was signed by ESO’s Director General Xavier Barcons and Alain Schuhl, the Deputy CEO for Science at the French National Centre for Scientific Research (CNRS), the institution leading the MOSAIC consortium. Also in attendance were the MOSAIC Principal Investigator Roser Pello from Marseille Astrophysics Laboratory and Co-Principal Investigator Mathieu Puech from the Paris Observatory, in addition to other dignitaries from ESO, CNRS and the MOSAIC consortium. The signing took place at the ESO Headquarters in Garching, Germany.
Sweden is part of the MOSAIC consortium through the Swedish ELT Instrument Consortium (SELTIC), which contains scientists and engineers from Stockholm, Uppsala and Lund Uinversity. At Stockholm University, Göran Östlin, Arjan Bik, and Jens Melinder at the Department of Astronomy are involved in the construction (more specifically in writing the software that will be used to reduce and interpret the data).
ESO's ELT under construction at Cerro Armazones. In the backgound the MIlky Way and the guiding laser from ESO's VLT at Cerro Paranal can be seen. Photo: ESO.
ESO’s ELT is currently under construction in Chile’s Atacama Desert, a unique place on Earth to observe the skies. When it sees first technical light later this decade, the ELT will revolutionise what we know about our Universe and make us rethink our place in the cosmos.
The MOSAIC project is managed by an international consortium composed of research institutes in 13 countries. They are:
- Austria: University of Vienna; Institute of Science and Technology Austria (ISTA)
- Brazil: National Astrophysics Laboratory; University of São Paulo
- Finland: University of Helsinki; Finnish Centre for Astronomy with ESO, University of Turku
- France: National Institute for Earth Sciences and Astronomy at the National Centre for Scientific Research (CNRS-INSU) ; UNité d'Ingénierie et de Développements Instrumentaux pour l'Astrophysique (UNIDIA) and Laboratoire d'étude de l'Univers et des phénomènes eXtrêmes (LUX); Institute for Research in Astrophysics and Planetology at the University of Toulouse; Marseille Astrophysics Laboratory. Laboratoire Joseph-Louis Lagrange (LAGRANGE)
- Germany: Leibniz Institute for Astrophysics Potsdam; LSW Heidelberg
- Italy: INAF Roma
- Netherlands: Netherlands Research School for Astronomy; University of Amsterdam
- Portugal: Centro de Investigação em Astronomia/Astrofísica da Universidade do Porto;FCiências.ID - Universidade de Lisboa
- Spain: Universidad Complutense de Madrid; Instituto de Astrofísica de Andalucía,IAA-CSIC
- Sweden: Stockholm University; Lund University; Uppsala University
- Switzerland: University of Geneva; École polytechnique fédérale de Lausanne
- United Kingdom: Durham University; University of Oxford / RAL Space; UK Astronomy Technology Centre
- United States: University of Michigan; Space Telescope Science Institute.
More about ELT and MOSAIC
Read more about ESO's ELT.
Read more about MOSAIC at the consortium web pages.
Contact at Stockholm University
Göran Östlin, 08-553 785 13, ostlin@astro.su.se
Jens Melinder, 070-6471856, jens@astro.su.se
Last updated: 2025-12-08
Source: Department of Astronomy