The map, made up of 263,407 exposures taken over 2,285 nights and containing 5.6 trillion pixels, covers about 75% of the sky and is used by DESI to select galaxies and quasars for 3D mapping of the universe and to study dark energy.
The DESI imaging survey team has released what it describes as the largest two-dimensional color map of the universe ever created. The dataset contains 5.6 trillion pixels and nearly four billion celestial objects—mostly stars and galaxies—covering about 75% of the sky in visible and near-infrared light.
The map is the result of 13 years of work, combining 263,407 telescopic exposures taken over 2,285 nights. More than 160 scientists participated in the data collection, and a team of 20 researchers and computer scientists produced the final dataset.
The entire database is open for scientific and public use. It can be explored using Legacy Survey's interactive sky viewer, to get closer to galaxies and familiar objects and to examine wide areas of the sky.
Map of the sky – no distance to every galaxy
Despite the nickname “map of the universe,” it is important to emphasize that this is a two-dimensional map. It records the angular positions of objects across the sky and their brightness in several light fields, but does not provide an accurate distance measurement for each of the nearly four billion objects.
In this sense, the map is like an extremely deep and wide photograph of the sky. It shows where each object is from our perspective, but not necessarily whether it is close to us or billions of light years away.
The third dimension is added by the Dark Energy Spectroscopic Instrument, DESI. The instrument splits the light from galaxies and quasars into spectra and measures their redshift. From the redshift, it is possible to estimate the distance of the object and the speed at which it is moving away from us due to the expansion of the universe.
The two-dimensional map thus serves as a vast target catalog: it tells DESI which objects to point its 5,000 robotic fiber optics at. The spectroscopic measurements turn part of the catalog into a three-dimensional map of the distribution of galaxies over billions of years of cosmic history.
Three ground surveys and one satellite
The map was compiled from observations from three major sky surveys. The DECaLS survey used the DECam dark energy camera, mounted on the Victor M. Blanco Telescope at Cerro Tolulo Observatory in Chile. The MzLS survey was conducted on the Mayall Telescope at Kitt Peak Observatory in Arizona, while the BASS survey was conducted at the Steward Observatory at the University of Arizona.
The ground-based data was supplemented by observations collected over years by NASA's WISE mission, which surveyed the sky in infrared radiation, as well as public data from other sources.
The combination makes it possible to distinguish between different types of objects and even identify faint and distant galaxies. However, dust and stars in the Milky Way obscure parts of the extragalactic universe, so even a map covering three-quarters of the sky is not a complete census of all objects in the observable universe.
Eight weeks of supercomputer processing
Combining hundreds of thousands of exposures into a single map required researchers to deal with differences in atmospheric conditions, camera sensitivity, image sharpness, and brightness calibration. The development of the software required to process the data took about a year.
The actual image processing took eight weeks on the Perlmutter supercomputer at the US National Energy Research Scientific Computing Center, NERSC. The result is not just a large image, but a database where objects can be searched by location, color, brightness and other properties.
Previous versions of the Legacy Surveys have been cited in more than 1,800 scientific papers. Researchers have used them, among other things, to search for gravitational lenses, identify transient events such as supernovae, study galaxies, and select targets for follow-up observations.
The infrastructure for DESI's 3D map
The original purpose of the imaging surveys was to prepare the DESI target list. The instrument is mounted on the four-meter-diameter Mayell Telescope and can measure the spectra of thousands of objects in a single exposure.
In April 2026, DESI completed its initial observing program ahead of schedule. In its first five years, the instrument measured more than 47 million galaxies and quasars and about 20 million stars. Since June 2026, the expanded version of the new map has been used to select additional targets, and observations are expected to continue until 2028.
The three-dimensional distribution of galaxies allows scientists to measure how the expansion rate of the universe has changed. Early DESI results have hinted that the influence of dark energy may change over time, but this is not yet a proven discovery. A more precise analysis of the five years of data is expected to be published in 2027.
A resource also open to researchers in Israel
Because the map and catalog are open to the public, researchers, students, and astronomy enthusiasts in Israel can also use them without needing to spend time observing at the telescopes that produced them. They can compare local observations with the data, locate familiar objects, and search for candidates for rare phenomena.
Opening up the data is especially important in the era of large-scale sky surveys. The database can serve as a basis for comparison with new observations from the Vera Rubin Observatory and the Nancy Grace Roman Space Telescope, as well as for training artificial intelligence systems designed to analyze petabytes of astronomical data.
According to David Schlegel of Lawrence Berkeley National Laboratory, one of the leaders of the Legacy surveys, the map has already become part of the infrastructure of astronomical research: researchers examining a celestial object often begin by examining it in the survey's visualization viewer.
Arjun Dey of NOIRLab, also one of the survey leaders, emphasized that in addition to contributing to the study of the expansion of the universe and the formation of galaxies, opening the database allows anyone to explore the sky and examine for themselves the objects recorded in it.
Questions and Answers
What does the term “two-dimensional map of the universe” mean?
The map shows the location of objects across the sky and their brightness in different light bands. It does not include spectroscopic distance measurements for each of the nearly four billion objects, and is therefore not a full three-dimensional map.
How does DESI add the third dimension to the map?
DESI measures the spectrum and redshift of galaxies and quasars. From the redshift, it is possible to estimate their distance and locate them in the depths of the universe, and not just by the direction in which they appear in the sky.
Why is mapping galaxies important for studying dark energy?
The clustering patterns of galaxies at different times preserve information about the expansion of the universe. Comparing the patterns over cosmic time allows us to examine how the rate of expansion has changed and whether the influence of dark energy is constant or evolving.
Can the public view the map?
Yes. The map is open free of charge via Legacy Survey Sky ViewerYou can search for objects by name or coordinates and change the zoom level and observation layers.
Source/Original article
- NOIRLab's official announcement
- Lawrence Berkeley National Laboratory Announcement
- DESI Legacy Imaging Surveys website
- The interactive map viewer
More on the subject on the science website
- The largest 3D map of the universe has been completed and will help study dark energy
- Rubin Observatory releases COSMOS image of more than half a million galaxies
- The giant camera at the Rubin Observatory is launched
- The Roman Space Telescope will be fueled and ready for launch on August 30th.
- James Webb Space Telescope reveals sharpest map of the cosmic web
For the original publication: Opening the original publication
