Data Processing

The Science Ground Segment 

The Euclid Consortium Science Ground Segment (EC SGS) is responsible of the design, development tests, integration and operation of the data processing tools, pipelines and data centers. The highest-level break-down of the Euclid pipeline is represented below:

SGS Organisation


The Organisation Units (OUs) represent self-contained processing units and constitute a first step into the realisation of a distributed pipeline development. They are listed hereafter:

  • OU-VIS: is in charge or processing the visible imaging data from level 1 to level 2. It produces fully calibrated images, as well as source lists for quality check purposes only.
  • OU-NIR: is in charge of processing the near-infrared imaging data from level 1 to 2. It produces fully calibrated images as well as source lists for quality check purposes and to allow spectra extraction.
  • OU- SIR: is in charge of processing the near-infrared spectral imaging data from level 1 to 2. It produces fully calibrated spectral images and extracts spectra in the slitless spectroscopic frames taken by the NISP. 
  • OU-EXT: is in charge of ingesting all external data. This is mostly multi-wavelength data for photo-z estimation, but also spectroscopic data to validate the spectrometric redshift measurement tools.
  • OU-SIM: realises the simulations needed to test, validate, and qualify the whole pipeline, science products included.
  • OU-MER: realises the merging of all the level 2 information. It is in charge of providing stacked images and source catalogues where all the multi-wavelength data (photometric and spectroscopic) are aggregated.
  • OU-SPE: extracts spectroscopic redshifts from the level 2 spectra.
  • OU-PHZ: computes photometric redshifts from the multi-wavelength imaging data.
  • OU-SHE: computes shape measurements on the visible imaging data.
  • OU-LE3: computes the high-level science data products (Level 3), using the fully processed shape and redshift measurements. 

The Science Data Center

The backbone of the science ground segment is formed by the SDCs, located in participating countries of the Euclid consortium. The SDCs are in charge of running different data processing functions of the Euclid pipeline. Inside an SDC a further distinction can be made between the production part of the SDC, which runs and maintains the pipelines and is referred to as SDC-PROD, and the development part of the SDC, that participates in all the software development needed for the SGS and is referred to as SDC-DEV.

CEA implication in the SGS:

The scientists of the Service d'Astrophysique have several responsibilities in the Science Ground Segment: 

The SGS Scientist is M. Sauvage 

In OU-LE3 (lead J.L. Starck):

  • WP Weak Lensing Implementation (lead J.L. Starck)
  • WP Internal Data Implementation (lead S. Pires)
  • WP External Data Validation (lead M. Kilbinger


  • WP Shape measurement Validation (lead M. Kilbinger)

The SDC-FR DEV- LE3 pipeline Implementation is S. Pires

 There is also a number of scientists participating actively to OU-LE3, OU-SHE, OU-VIS.

SAp and SEDI members involved in the activity:
Amiaux Jérôme, Bobin Jerome, Cuillandre Jean-Charles, Gastaud Rene, Kilbinger Martin, Bertrand Morin, Okumura Koryo, Paulin-Henriksson Stéphane, Pierre Marguerite, Pires Sandrine, Pratt Gabriel, Ronayette Samuel, Sauvage Marc, Starck Jean-Luc, Florent Sureau


This webpage is in construction for any comment or feedback, send an email to Sandrine Pires 
Last modified in February 4th, 2015 by Sandrine Pires