The 35th annual conference on Astronomical Data Analysis Software & Systems 2025 in Görlitz, Germany

The Euclid satellite is an ESA mission that launched in July 2023. Euclid targets to observe an area of 14,000 deg^2 with two instruments, the Visible Imaging Channel (VIS) and the Near IR Spectrometer and imaging Photometer (NISP) down to VIS=24.5mag (10 sigma). Ground based imaging data in griz from surveys such as the Dark Energy Survey and Pan-STARRS complement the Euclid data to enable photo-z determination.

After the Quick Data Release 1 (Q1), that published 63.1 deg^2 of wide-survey science data publicly in March 2025, the focus has shifted to the preparation of Data Release 1 (DR1). As the first large data release of Euclid DR1 is scheduled for November 2025 internally (public release: November 2026) and has a sky coverage of about 1900 deg^2.

In this contribution we discuss the data processing for DR1, which required the coordination of several processing pipelines for various input data (VIS, NIR and external) that are run on thousands of CPU's distributed internationally over several dedicated data centers. We will put a particular focus on the generation of the the multi-wavelength catalogs of Euclid and ground based data, which is a central part of the Euclid data processing system. We show the different photometric measurements we offer to our users and show that these fulfill the tight requirements on photometric accuracy. We also present the other measurements such e.g. morphology that are included in our catalogs. We list all output products of the cataloging pipeline which go far beyond the object catalogs.

For the processing of this vast amount of data the automatic validation of the results has become a central issue, and we show the software and procedures we developed and implemented to achieve this difficult task with a minimum of interactive work.