Euclid is a major mission of the European Space Agency (ESA) Cosmic Vision programme. This international reference mission in cosmology aims to understand the source of the accelerating expansion of the universe, the nature of dark energy and gravitation through the observation of several billion galaxies, tracing the history of the universe over more than 10 billion years.

The scale of this mission requires an organisation - the Euclid Consortium - that brings together around 2,000 researchers, engineers and technicians from all European countries, with participation from the USA, Canada and Japan. As a major participant in this project, France, via CNES, has provided the laboratories with the means to contribute to this mission. With about 250 active Euclid members in France - including the mission's scientific leader (Yannick Mellier, IAP) and his deputy (Francis Bernardeau, IAP) - CNES, CNRS, CEA and the partner universities are providing significant human resources and technical infrastructure.

In Lyon:

Lyon's Institut de Physique des 2 Infinis (IP2I) has been involved in the Euclid mission from the very beginning and has among its founders and builders of the project. IP2I members were engaged in the selection and characterization of the near-infrared detectors for one of Euclid's instruments. Thanks to their experience in analyzing signals from infrared detectors and in spectroscopic data reduction, IP2I is involved in the ground segment organizational units dedicated to data processing (OU-SIR and OU-NIR) for the near-infrared spectrophotometer NISP. IP2I is co-lead of the OU-SIR group and has responsibilities in the calibration and instrument operation teams: in particular, IP2I hosts a spectroscopy calibration deputy lead and detector scientist for the NISP detectors. With its experience in cosmological simulations and analysis of galaxy velocities in the near universe, IP2I is also contributing to the activities of scientific working groups using Euclid data.

The Laboratoire des Matériaux Avancés (LMA) is involved in the PSF reconstruction effort by measuring the chromatic behaviour of the dichroic mirror wavefront error (WFE). For this purpose, LMA is measuring the WFE of the dichroic mirror Flight Spare in various angles of incidence, polarisation states and over a very large spectral range. This activity relies on an innovative optical bench funded by ESA featuring outstanding and unprecedented performances. The data acquired from the Flight Spare will enable to build up a complete model of the dependency of the WFE on the wavelength that will be then included in the PSF reconstruciton pipeline.

The Centre de Recherche Astrophysique de Lyon (CRAL) is contributing to the several science working groups of the Euclid mission, including galaxy evolution (with one work package lead in the SWG) and theoretical cosmology. CRAL is also a key member of the 4 meter Multi-Object Telescope (4MOST) consortium which has an agreement with Euclid to share data and will observe common fields, allowing for a combination of photometric and spectroscopic data. CRAL is leading the 4MOST Cosmology Redshift Survey and contributing to the 4MOST follow-up of Euclid-selected strong lenses.

The Centre de calculs de l'IN2P3 (CC-IN2P3) is the French science data center and as such provides computing and storage infrastructure for the Euclid mission, as well as user support.

A few months after its launch, as the satellite undergoes its final steps of the performance verification phase , we have just published the EROs and are preparing to begin the nominal survey, we invite you to meet us to take stock of Euclid's activities in France, identify the areas that need to be strengthened and plan the scientific exploitation of the first available data.