【#Tech 24H】The DESI Legacy Imaging Surveys team has released the largest twodimensional color map of the universe to date. This vast 5.6trillionpixel mosaic holds nearly four billion celestial objects, predominantly stars and galaxies. Covering roughly 75？percent of the sky across visible and nearinfrared bands, the map precisely documents the positions and brightness of galaxies and stars. It enables DESI to select observation targets, measure light across different wavelengths and derive distances, laying the groundwork for the highestresolution threedimensional map of the universe ever produced. This spectacular sky map was assembled from hundreds of thousands of images taken over 2,285 nights. Each image bears the unique signatures of atmospheric conditions and telescope settings at the time of observation, and the entire project demanded monumental computational resources. Scientists at the U.S. Department of Energy’s National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory spent about one year developing the code. They then ran eight consecutive weeks of aroundtheclock computations on the Perlmutter supercomputer to finish processing and assembling all the imagery. [ By Zhang Liyan ]