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MOSAIC : the Paris-PSL Observatory at the heart of building the instruments for the future ELT

2 décembre 2025

On December 1, 2025, ESO signed the agreement launching the design and construction of MOSAIC, the multi-object spectrograph for the Extremely Large Telescope (ELT), on which teams from the Paris Observatory – PSL have been working for the past ten years. Capable of observing more than 200 sources simultaneously, MOSAIC will enable the mapping of matter from the earliest epochs of the Universe.

A leading role in an international consortium

The Paris Observatory–PSL plays a strategic role in this consortium. Mathieu Puech (LUX) is co-director of the project ; at UNIDIA, Hermine Schnetler is the project manager and Myriam Rodrigues is the systems engineer, assisted by Alondra Sola-Molina, a recently recruited young engineer. This triple involvement places the Observatory at the center of the scientific and technical management of a consortium bringing together 14 countries, more than 30 laboratories, and 260 researchers.

L'équipe du projet MOSAIC (Roser Pello, Mathieu Puech, Myriam Rodrigues, Hermine Schnetler, Patrick Caillier, Alessandro Melo, Oliver Pfuhl, Cyrielle Blanc) lors de la cérémonie de signature pour l'instrument. Alain Schuhl (directeur général adjoint pour la science, CNRS) et Xavier Barcons (directeur général, ESO) sont au premier plan.
De gauche à droite : Alessandro Melo, Cyrielle Blanc, Oliver Pfuhl, Roser Pello, Myriam Rodrigues, Hermine Schnetler, Mathieu Puech, et Patrick Caillier
crédit : ESO

A lever for expertise and attractiveness

This leadership strengthens international recognition of the institution’s expertise : mastery of systems engineering, ability to coordinate very large-scale projects, and development of skills in the instruments that will shape the astronomy of tomorrow. It also contributes directly to the Observatory’s attractiveness, drawing young talent motivated by the complexity and ambition of MOSAIC.

By taking part in the design and construction of iconic ELT instruments such as MOSAIC, the Paris Observatory is more than ever asserting its place among the major players in global astronomical instrumentation.

Resources :

● https://observatoiredeparis.psl.eu/une-avancee-technique.html
● https://observatoiredeparis.psl.eu/lancement-officiel-de-mosaic.html
● https://observatoiredeparis.psl.eu/mosaic-sur-l-elt-un-pas-de-3704.html

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