5.6-Trillion-Pixel Sky Mosaic Goes Live — and Why It's Not the 'Largest 3D Map'

Forum topic · QianXun · 2026-09-08

Summary

On August 10, 2026, Data Release 11 (DR11) of the DESI Legacy Imaging Surveys went online: a 5.6-trillion-pixel image cataloging about 3.92 billion unique objects across 30,516 square degrees (74% of the sky), built from 13 years of imaging with three telescopes plus NASA's WISE satellite (263,407 exposures over 2,285 nights). The post criticizes WIRED Japan's September 7 coverage, which conflated this two-dimensional mosaic with DESI's separate three-dimensional spectroscopic map of 47 million galaxies and quasars with distance measurements — announced in June 2026 as the largest 3D cosmic map. The two projects are complementary: the imaging survey supplied target selection for DESI's 5,000-fiber spectrograph on the Mayall 4-meter telescope at Kitt Peak, while DESI's distances annotate the photo catalog. The post also reviews the evolving dark energy story: hints that dark energy may weaken (up to 4.2 sigma in 2025 three-year data) retreated to 1.4 sigma in later joint analyses, with a verdict expected from full five-year DESI data around 2027. DR11 data is freely explorable at legacysurvey.org/viewer and already supports over 1,800 papers.

The mix-up WIRED made

On August 10, 2026, Data Release 11 (DR11) of the DESI Legacy Imaging Surveys quietly went online: a 5.6-trillion-pixel image containing about 3.92 billion objects, covering three-quarters of the sky — the product of thirteen years of imaging. On September 7, WIRED Japan published an enthusiastic feature calling it "the largest 3D map of the universe." That was the mistake: this is a two-dimensional photograph, not a 3D map.

Two surveys, two "largest"

The imaging survey (2013–2024): 263,407 exposures over 2,285 nights, using three telescopes plus NASA's WISE infrared satellite. DR11 is the result — a 5.6-trillion-pixel, 2D mosaic of the extragalactic sky.
DESI spectroscopic survey (2021–2026): mounted on the Mayall 4-meter telescope at Kitt Peak, with 5,000 robotic fiber positioners, it completed its five-year main survey early in April 2026 — 47 million galaxies and quasars, each with a measured redshift and distance. That is the actual "largest 3D map," announced June 4, 2026.

The imaging survey told DESI where to point; DESI's distances now annotate the objects in the photo. NOIRLab's press release distinguishes the two clearly. (WIRED also misspelled co-lead Arjun Dey as "Arjun Day" and inflated his title.)

What DR11 actually is

3.92 billion unique objects: ~2.2 billion point sources (stars, quasars) and ~1.7 billion resolved galaxies
30,516 square degrees, 74% of the sky; four optical bands plus infrared; galactic plane honestly left blank
Processed on the Perlmutter supercomputer over roughly eight weeks
Pixel scale six orders of magnitude beyond a phone camera; over 1,800 papers already cite the data

It is genuinely explorable, free and without registration, at legacysurvey.org/viewer — zoom from the all-sky view to single galaxies, search by coordinates or object name, and compare a dozen survey layers (Pan-STARRS, SDSS, DES, etc.).

Dark energy: not this map's story

The intriguing dark energy hints belong to DESI's spectroscopy line, and the plot has cooled:

2024 (first-year data): evolving dark energy favored over a cosmological constant at 2.6–3.9 sigma
2025 (three-year data): preference peaked at 4.2 sigma
Late 2025: joint analyses with CMB and supernovae compressed the difference to 1.4 sigma
July 30, 2026: Lyman-alpha forest full-shape analysis swung back toward constant cosmology
~2027: the full five-year data delivers the verdict

DR11's role is infrastructure: DESI's target-selection catalog, a reference frame for future Rubin and Roman surveys, and training data for AI tools in the DOE's Genesis Mission astrophysics pilot.

Takeaway

Next time you see "largest map of the universe," ask: how many dimensions? 5.6 trillion pixels / 3.9 billion objects = the 2D photo (DR11). 47 million galaxies with distances = DESI's 3D spectroscopic map, where the dark energy verdict will come from. One is the universe's group photo; the other, its medical checkup. The photo is done; the checkup report arrives around 2027.

Sources: NOIRLab press release noirlab2620 and Berkeley Lab release (both 2026-08-10); legacysurvey.org DR11/DR10 pages (3,920,661,806 unique sources; 30,516 deg²); WIRED Japan/US feature (Ritsuko Kawai, 2026-09-07); DESI DR2 official guides and NOIRLab 2026-06-04 announcement.