Euclid DR1 data release: a billion objects, with cosmology results due 2027

ESA’s Euclid space telescope has made public about 13 months of observations covering roughly 1,900 square degrees of sky and more than a billion catalogued objects, but the weak-lensing measurements that will turn this into cosmology are not due until June 2027.

Official announcement · Public data release (images, spectra, catalogues) · Not yet a cosmology result

The European Space Agency (ESA) and the Euclid Consortium released DR1-Foundation on 12 November 2026, the first large batch of data from the Euclid survey telescope. It holds images, spectra and catalogues for more than a billion stars, galaxies and quasars across a patch of sky about as large as 9,500 full Moons. That makes it the base layer for Euclid’s planned 3D map of the Universe. The catch is in the name: this is the foundation. The dark-matter and dark-energy measurements Euclid was built for arrive with the rest of DR1 next June.

Evidence at a glance

Is this a big deal?

For astronomers, yes: it is a mission milestone and far bigger than anything Euclid has shared before. For the questions Euclid was built to answer, it is a solid step, not a result. Nothing in this release says anything new about dark energy yet. What it does deliver right away is a huge public catalogue in which rare objects, such as strong gravitational lenses, can be found in bulk.

What scientists found

The release covers about 1,900 square degrees of Euclid’s Wide Survey, which ESA puts at 14% of the sky area the mission will cover. Adding the deep fields and calibration fields brings the total to roughly 2,000 square degrees, says the overview paper. For scale, the whole sky is about 41,250 square degrees, so this is close to one twentieth of it.

Inside that area, the team catalogued more than a billion sources. Just over 900 million are classed as galaxies: 817,846,065 in the Wide Survey, 49,393,051 in the deep fields and 34,427,023 in the auxiliary fields, the paper lists. That works out, by SciQuest’s calculation, to roughly 80,000 Wide Survey galaxies in a patch of sky the size of the full Moon.

The headline science so far is strong lensing. A strong lens forms when a massive foreground galaxy bends the light of a more distant one into arcs or rings. Natalie Lines of the University of Portsmouth and colleagues report 15,072 high-confidence candidates: 6,073 graded “sure” and 8,999 “probable”. ESA says that is more than all previous lens catalogues combined.

How they found it

Euclid launched on 1 July 2023 and started its survey on 14 February 2024 from an orbit around the Sun-Earth L2 point. It carries a 1.2-metre mirror and two instruments. VIS takes sharp visible-light images, and NISP takes near-infrared images and also spreads light into spectra without a slit, which lets it record spectra for many objects in one exposure.

The first year was not smooth. Ice built up inside the VIS instrument and cut its throughput, and the team ran decontamination procedures to clear it on 14 March and again on 8 June 2024, the overview paper says. Since then, VIS sensitivity has dropped by only 1 to 1.5% over about 2.5 years.

The “3D” comes from distance. Light from a far galaxy is stretched to redder wavelengths as the Universe expands, and that stretch, the redshift, tells astronomers how far away it is. DR1-Foundation gives estimated redshifts from colours for 880 million Wide Survey sources and extracts a spectrum for every catalogued object brighter than magnitude 23.5 in NISP’s H band. In those spectra, ESA says, scientists will look for the hydrogen-alpha line to pin down distances. Checked against the ground-based DESI survey, the redshifts scatter half as much as in Euclid’s March 2025 quick release.

Think of the release as a national census in which the forms have been collected, checked and filed, but the statistics office has not yet published its report. The analogy has a limit: unlike census forms, many entries are still candidates whose identity is unconfirmed.

“These are far more than beautiful pictures; today marks a scientific milestone in our study of the cosmos,” said Carole Mundell, ESA’s Director of Science, in the release.

Why it matters to you

This won’t change anything in daily life. It belongs in the “wonder” column: most of the Universe’s energy budget is attributed to dark energy, and nobody knows what it is. Euclid was designed to test how it has behaved over cosmic time. Unusually, you can look at the data yourself. The release is open through ESA’s Euclid Data Space, and volunteers on the Space Warps citizen-science project helped sort the lens candidates. Our explainer on what the Universe is made of covers the dark-energy background.

What the evidence does not show

It does not show a 3D map of the cosmic web yet. The distances exist as catalogue entries, but turning them into a map that can test cosmology needs the selection functions and clustering statistics scheduled for full DR1. The overview paper states that “the shear measurements and the ‘Level 3’ products required for cosmological analyses” will be added in June 2027.

The redshifts need care. Because NISP extracts a spectrum for everything above its brightness cut, the authors caution users “against blindly using the redshifts”: many spectra show no measurable features but still appear in the catalogue with an entry. Quality flags are provided to sort them.

The lens and quasar numbers are candidates. The 60 million quasars were picked out from colours, not confirmed one by one. And NISP’s blue-grism data are not yet corrected for a slow sensitivity drift caused by ice, the paper notes.

How this fits what we already knew

Euclid’s earlier releases were tasters. The Early Release Observations showed 24 hours of data, and ESA says the previous releases covered a few days of observations over about 60 square degrees. “We’re now releasing more than a year of data covering a significantly larger area,” said Valeria Pettorino, ESA’s Euclid project scientist.

The figures differ slightly depending on where you read them, and the gap is about definitions, not errors. The table below reconciles them.

To make 1.7 petabytes concrete: it would fill about 1,700 one-terabyte laptop drives.

Independent view

SciQuest has not yet obtained comment from an astronomer outside the Euclid Consortium; the request is logged with our editors. Every scientist quoted in the coverage we found works on Euclid or for ESA. The most useful independent check so far is internal to the data: the comparison with DESI redshifts described above.

How other headlines framed it

• ESA framed the release as laying the foundation for a 3D map, which matches what the data contain.
• Phys.org’s repost of the Max Planck Society release ran a headline saying Euclid “offers” its best-ever 3D map, which reads as if the map were finished; the text underneath describes a foundation.
• Leiden University’s release said Euclid sets a new standard for cosmology, while noting that the first cosmology analyses are due in June 2027.
• Sky & Telescope led with the scale of the data haul and placed the cosmology in mid-2027.
• Universe Today, via Phys.org, called it a stepping stone toward the 3D map.

What happens next

The full DR1 is listed by ESA for 16 June 2027. It will add the weak-lensing shear measurements, the subtle distortions in the shapes of background galaxies, plus galaxy-clustering statistics, and it will reuse the DR1-Foundation products rather than reprocess them. By the time the overview paper was written, Euclid had already observed about 8,700 square degrees; those data feed DR2, scheduled for 2029. The last survey observation is planned for 2 January 2030. NASA’s Roman Space Telescope is chasing the same dark-energy questions with a different survey design. We’ll cover the June 2027 cosmology results when they appear.

In one sentence

Euclid has opened a public catalogue of more than a billion objects over about 1,900 square degrees, the raw material for its 3D map, while the dark-energy tests that map is meant to deliver are due in June 2027.

Read next

• NASA’s Roman Space Telescope launch: the other big survey mission chasing dark energy.
• Where dark matter is found: the invisible mass that strong and weak lensing trace.
• A close quasar pair at cosmic dawn: the kind of rare object large surveys turn up.

Sources and disclosure

1. ESA. “Euclid lays the foundation for its best-ever 3D map of the Universe.” 12 November 2026. Source of the counts, the 9,500 full Moons comparison, the 14% figure and both quotes.
2. Euclid Collaboration: H. Aussel et al. “Euclid First Data Release 1 (DR1): Data release overview.” Astronomy & Astrophysics manuscript, 12 November 2026; arXiv:2611.16510. Source of the areas, galaxy breakdown, spectra, redshift caution, mission dates, ice history and DR2 schedule.
3. Euclid Collaboration: N. E. P. Lines et al. “Euclid Data Release 1 (DR1). ECLIPSE A: Strong lens catalogue overview.” arXiv:2611.15883, submitted 11 November 2026.
4. ESA Cosmos. Euclid Data Release DR1 (release dates: DR1-Foundation 12 November 2026; DR1 16 June 2027).

Disclosure: This article was drafted with AI assistance and checked against the sources above. The galaxies-per-Moon figure (817.8 million galaxies ÷ 1,975 deg² × 0.2 deg² per full Moon, using ESA’s 1,900 deg² = 9,500 Moons equivalence), the whole-sky fraction (1,900 ÷ 41,253 deg²) and the drive comparison are SciQuest calculations; the timeline graphic is a SciQuest original drawn from ESA and Euclid Collaboration figures. Spotted an error? See our corrections policy.