The DESI Legacy Imaging Surveys team released the largest two-dimensional color map of the universe ever assembled, covering roughly three-quarters of the sky in visible and near-infrared light. Announced jointly on August 10 by the Lawrence Berkeley National Laboratory and NSF NOIRLab, the 5.6-trillion-pixel atlas catalogs nearly 4 billion celestial objects and is freely available to the public.
DESI Releases Largest 2D Universe Map Cataloging 4 Billion Objects
The massive dataset combines 263,407 individual exposures collected over 2,285 nights of observation. Input data came from three ground-based programs: the Dark Energy Camera Legacy Survey at Cerro Tololo Inter-American Observatory in Chile, the Mayall z-band Legacy Survey at Kitt Peak National Observatory (KPNO) in Arizona, and the Beijing-Arizona Sky Survey operated through the University of Arizona’s Steward Observatory. These ground-based observations were supplemented by years of data from NASA’s Wide-field Infrared Survey Explorer (WISE) satellite and other public archives.
Engineering the 5.6-Trillion-Pixel Universe Atlas
Creating a cohesive map from observations gathered across different telescopes and years required extensive software calibration. Aligning measurements so that a star recorded in Chile in 2015 matched the brightness of the same star measured in Arizona in 2023 required roughly a year of software development. Once the code was ready, the team processed the images continuously for eight weeks using the Perlmutter supercomputer at the National Energy Research Scientific Computing Center (NERSC) at Berkeley Lab.
It’s part of the fabric of astronomy research now,
said David Schlegel, a co-lead of the Legacy Surveys and a scientist at Berkeley Lab. When you're working with astronomical objects today, you often start by pulling up the Legacy Imaging Viewer to see what you’re looking at.
More than 160 scientists contributed to the project, while a 20-member team assembled the final dataset. The catalog includes stars, galaxies, asteroids, black holes, supernovae, and gravitational lenses, providing a deep view of regions beyond the Milky Way where dust does not obscure distant objects.
Active Infrastructure and Future Astronomical Surveys
Unlike three-dimensional spectroscopic surveys that measure the Doppler shift in an object’s light to determine distance, the new release is an imaging map that records positions and brightnesses across multiple wavelengths. However, the map serves as active infrastructure for ongoing research. Since June, the expanded 2D dataset has guided the nightly observing runs of the Dark Energy Spectroscopic Instrument (DESI), which is installed on the Nicholas U. Mayall 4-meter Telescope at KPNO.
DESI completed its primary five-year survey ahead of schedule in April, having measured cosmological data for six times as many galaxies and quasars as all previous measurements combined, though observations are continuing under an extended program through 2028. The collaboration expects to publish improved results from its first five years of operations in 2027.
The new 2D catalog will also support upcoming facilities by acting as a reference baseline. Researchers will cross-match detections from the Vera C. Rubin Observatory against the DESI Legacy Surveys catalog to track new or moving objects, while NASA’s Nancy Grace Roman Space Telescope will rely on the catalog for target identification and calibration during its early operations.
For our team, these data are fundamental to our investigation of the expansion history of the universe and the formation of our galaxy,
said Arjun Dey, co-lead of the Legacy Surveys and an astronomer at NSF NOIRLab. But the skies belong to everyone, and this survey gives everyone the chance to explore the sky and marvel at its wonders.
