The largest observation program of the James Webb Space Telescope (JWST) has released its data: nearly 800,000 galaxies observed in unprecedented detail. COSMOS-Web thus offers the most extensive and deepest view of the universe ever obtained. In this data release, the Instituto de Astrofísica de Canarias (IAC) has played a key role, performing the morphological classification of more than half a million galaxies using neural networks, a crucial contribution to explore how galaxies form and evolve over cosmic time.
COSMOS-Web was the largest General Observer program selected for Cycle 1 of the JWST. While previous surveys have aimed to help astronomers map and understand what exists in the vast universe, the advanced instruments of JWST have allowed COSMOS-Web to study galaxy evolution through a long range of history.
“The sensitivity of JWST lets us see much fainter and more distant galaxies than ever before, so we’re able to find galaxies in the very early universe and study their properties in detail,” said Jeyhan Kartaltepe, associate professor at Rochester Institute of Technology and lead researcher of COSMOS-Web. “The quality of the data still blows us away. It is so much better than expected,” adds Caitlin Casey, professor of physics at University of California, Santa Barbara, who is also leading the observation programme.
COSMOS-Web is part of The Cosmic Evolution Survey (COSMOS), an ambitious international project that, since 2007, brings together more than 200 scientists from around the world to understand how galaxies form and evolve. The result of this collective effort is COSMOS2025, the new catalogue that combines data obtained by JWST with observations from ground-based telescopes and information gathered in previous COSMOS studies. The result is an unprecedented dataset of nearly 800 000 galaxies, including details on their shape, brightness, distance and other physical properties, which is now available to the entire scientific community.

When the JWST launched in 2021, the COSMOS-Web team of nearly 50 researchers around the world had the longest observing time during the telescope’s first year. The survey mapped 0.54 square degrees of the sky (about the area of three full moons) with the Near Infrared Camera (NIRCam) and a 0.2 square degree area with the Mid Infrared Instrument (MIRI). While previous surveys have aimed to help astronomers map and understand what exists in the vast universe, the advanced instruments of JWST have allowed COSMOS-Web to study galaxy evolution through a long range of history, accumulating more than 250 hours of observations.
JWST's COSMOS-Web data have provided the information needed to achieve its three main goals: to map and build understanding of the Reionization Era (in the universe’s first billion years); to trace and identify massive galaxy evolution in the first two billion years; and to study how dark matter is linked to visible matter within galaxies.
‘Building the catalogue has been a huge team effort. The IAC's contribution has consisted of applying neural networks to measure the morphology of more than half a million galaxies included in this catalogue,’ says Marc Huertas-Company, IAC researcher and member of the COSMOS-Web team. ‘We are facing a paradigm shift in the use of artificial intelligence in astronomy; the JWST data not only open a new era in the observation of the cosmos, but also mark a decisive step towards more advanced tools that could accelerate our discoveries about the evolution of galaxies and the nature of the universe itself,’ he concludes.
Along with the data itself and three initial papers on the catalog, near infrared imaging, and mid infrared imaging, the data release also includes an interactive viewer where users can directly search images for specific objects or click on objects to see their properties.
More information:


