Euclid Explanatory Supplement
Data Release DR1-Foundation
Documentation release 1

Executive summary

The DR1-Foundation data release is the first part of Euclid DR1 Data Release. With DR1-Foundation, the Euclid Consortium and ESA releases the images, catalogs, spectra, redshifts both photometric and spectroscopic over $\sim$ 1900 deg${}^2$ of the Euclid Wide Survey, multiple passes of the Euclid Deep Fields and numerous calibration observations. It encompasses visible and near-infrared space-based imaging and spectroscopic data, ground-based photometry in the $u$, $g$, $r$, $i$, and $z$ bands, as well as corresponding masks.

Building on this DR1-Foundation, the forthcoming DR1 data release will additionally contain the shape measurements, the selection functions for weak lensing, galaxy clustering and cluster detection, cluster catalogs, and high-level products allowing for the derivation of the cosmological results.