Researchers launch REGALADE: The most complete galaxy catalogue for modern astronomy

An international team of scientists has introduced REGALADE (Revised Galaxy List for the Advanced Detector Era), an unprecedented all-sky catalogue that brings together nearly 80 million galaxies. This work, led by the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Institute of Space Studies of Catalonia (IEEC), marks a turning point for astronomy, enabling researchers to explore cosmic events with a level of precision never seen before. The results are published in the journal Astronomy & Astrophysics.

When a telescope detects a sudden phenomenon such as a supernova or the merger of two black holes or neutron stars, astronomers need to know where to look and how far away the event occurred. That requires identifying the galaxy hosting the event. Until now, existing catalogues were incomplete beyond about 300 million light-years, leaving large gaps in our map of the nearby Universe. REGALADE fills those gaps by combining data from major surveys and cleaning it using data from the Gaia mission to remove stars mistakenly classified as galaxies. The result is a high-purity, high-completeness catalogue that includes accurate distances and size measurements for all galaxies, and stellar masses for most.

“REGALADE began as a user experience problem: astronomers relied on many popular catalogues, but each one covered only part of the sky or lacked key information,” explains Hugo Tranin, ICCUB researcher and lead author of the study. “By merging data from 14 widely used catalogues and deep imaging surveys, we now have a single, unified place to look for galaxy distances and properties. This drastically simplifies the daily work of astronomers and allows our team to retrieve distances for more than 75% of the transients reported worldwide every day.” 

The team has also released an interactive sky viewer, where the public can explore the REGALADE catalogue and navigate millions of galaxies in just a few clicks. The scale and depth of REGALADE are extraordinary. It covers the entire sky and reaches out to more than four billion light-years, mapping about 10% of the volume of the observable Universe. This completeness means astronomers can now identify many more host galaxies for all types of cosmic events, from infrared to X-rays, and significantly improve strategies for gravitational-wave follow-up.

According to Nadia Blagorodnova, IEEC researcher at the ICCUB and co-author, “Observatories like the Vera Rubin Observatory will detect millions of cosmic events every night. REGALADE ensures we can identify their host galaxies quickly and accurately, enabling rapid classification of rare transients such as luminous red novae, stellar mergers that our team actively studies, and opening the door to the discovery of entirely new types of celestial phenomena.”

In addition to Hugo Tranin and Nadia Blagorodnova, the study involved IEEC-ICCUB researchers Marco A. Gómez-Muñoz and Maxime Wavasseur. Their work combines expertise in time-domain astrophysics, binary evolution, large astrophysical catalogues and multi-messenger astronomy, striving to build comprehensive resources for scientifically exploiting the new generation of ground-based and space-based time-domain surveys.

Lead Researcher at the IEEC

Nadejda Blagorodnova

Institute of Space Studies of Catalonia (IEEC)
Institute of Cosmos Sciences (ICCUB)
E-mail: blagorodnova@ieec.cat, nblago@fqa.ub.edu