The European Space Agency and Euclid Consortium released DR1-Foundation on November 12, 2026, making a major set of galaxy observations available for scientific research. The release draws on approximately 13 months of observations and includes Euclid Wide Survey coverage spanning 1,900 square degrees of sky.
ESA’s release announcement reports more than 900 million galaxies, approximately 15,000 strong gravitational-lens candidates, and spectra from more than 160 million sources. The observations capture visible and near-infrared light, providing different measurements of objects distributed across the surveyed sky.
DR1-Foundation is the first stage of Euclid’s Data Release 1. The complete release, expected in mid-2027, will add higher-level products used to study galaxy clustering and weak gravitational lensing.
Images and Spectra Serve Different Purposes
Euclid’s images record where objects appear and how their light is distributed. Spectra divide incoming light by wavelength. Features in a spectrum provide information about an object’s composition and can support measurements of its redshift, the stretching of light toward longer wavelengths.
The Paris Observatory’s release description identifies approximately 10,000 scientific images from the spacecraft’s two instruments. The visible-light instrument, VIS, supplies optical imaging. The near-infrared instrument, NISP, supplies imaging and spectroscopy at longer wavelengths.
The two instruments provide complementary measurements of the same broad survey. Astronomers can combine positions and image properties with spectral information to investigate the distribution of galaxies beyond a two-dimensional picture of the sky.
Euclid also repeatedly observes selected deep fields. Repeated exposures collect more information about faint objects than a single short observation. The Paris Observatory describes these fields as a route to studying distant galaxies as they appeared billions of years ago.
The survey’s 1,900-square-degree coverage represents approximately 14% of the area planned for Euclid’s six-year survey. That percentage refers to the planned survey footprint, rather than 14% of the entire sky.
Gravity Provides Another Measurement
Strong gravitational lensing occurs when a foreground concentration of mass bends light from a more distant object. Depending on the alignment, the background galaxy can appear as arcs or multiple images. Euclid’s candidate catalog gives researchers a large collection of possible systems to examine.
The light distortion carries information about the mass responsible for bending it. That connects visible images with the study of material whose gravitational influence can be measured even when it does not emit detectable light.
New Space Economy’s explanation of dark matter and dark energy distinguishes these two subjects. Dark matter is associated with gravitational effects attributed to unseen mass. Dark energy is the name given to the cause of the universe’s accelerating expansion. Euclid uses observations of cosmic structure and its development to investigate both.
Weak lensing concerns much smaller changes in galaxy shapes. Its analysis relies on patterns measured across many galaxies. The higher-level weak-lensing products scheduled for the complete DR1 release will complement the images and other measurements now being distributed.
Access Through Scientific Archives
The NASA/IPAC archive documentation describes several ways to work with the release. An interactive data explorer supports searches and visualization of images, catalogs, and spectra. Catalog-search services provide access to object records, and programmatic interfaces allow researchers to request data through software.
The archive distinguishes stacked imaging, multiwavelength mosaics, classification catalogs, and spectral products. Stacking combines exposures; mosaics join observations into larger views. Catalogs organize measurements into records that can be searched and compared.
For large analyses, NASA’s Fornax Science Platform places computing resources close to cloud-hosted data. Catalogs are being added to archive services incrementally.
For large analyses, the archive offers access through NASA’s Fornax Science Platform, which places computing resources close to cloud-hosted data. That arrangement lets researchers work with large collections without first transferring every file to a local computer. Catalogs are being added to archive services incrementally.
The Euclid Consortium includes more than 2,000 scientists from 300 institutes across 15 European countries, the United States, Canada, and Japan, according to the Paris Observatory. Its responsibilities include scientific instruments and the production and analysis of mission data.
DR1-Foundation supplies the observations for studies of galaxy populations, clusters, and other objects as the consortium prepares the complete DR1 products for release in 2027.
