Building a giant 2-D map of the universe to prepare for the largest 3-D map

Before DESI, the Dark Energy Spectroscopic Instrument, can begin its 5-year mission from an Arizona mountaintop to produce the largest 3-D sky map yet, researchers first needed an even bigger 2-D map of the universe.

source https://phys.org/news/2021-01-giant-d-universe-largest.html