The Sloan Digital Sky Survey V (SDSS-V) has released Data Release 20 (DR20), a sweeping expansion of its cosmic map that, for the first time, includes SDSS-V optical spectra gathered from the Southern Hemisphere — turning the 25-year-old survey into a truly two-hemisphere enterprise.
DR20 delivers more than three million spectra of stars and galaxies along with 18 value-added catalogs. The new southern observations were made with the 2.5-meter du Pont Telescope at Las Campanas Observatory in Chile, complementing the Sloan Foundation 2.5-meter Telescope at Apache Point Observatory in New Mexico. "DR20 represents an enormous leap in the scale of SDSS data products," said Emily Griffith of the University of Colorado Boulder, spokesperson for the SDSS-V collaboration.
The survey's Black Hole Mapper grows dramatically, carrying 3-to-4 times more data than DR19: roughly 1.1 million optical BOSS spectra covering about 500,000 distinct objects. That includes hundreds of thousands of X-ray-emitting active galactic nuclei, galaxy clusters and active stars identified and measured through the SPIDERS program, coordinated with the second release of the eROSITA X-ray all-sky survey — as well as time-domain monitoring of supermassive black holes from the AQMES and Reverberation Mapping programs.
Across the Black Hole and Milky Way Mappers, DR20 contains more than three million spectra covering 1.5 million stars, including the first carbon-enhanced metal-poor stars identified in the Magellanic Clouds and the first intermediate-mass stripped star — rare objects long sought for clues about how stars form and evolve.
The Local Volume Mapper also expands far beyond its single-tile preview, now offering integral-field spectroscopy maps of six target regions spanning 169 tiles and about 300,000 spectra, capturing objects such as the Rosette and Orion nebulae. A new browser-based tool, LVMvis, lets anyone explore the glowing gas structures.
Like previous releases, DR20 is cumulative and freely accessible through the Science Archive Server with tutorials. "The data should not just be publicly available but be publicly usable," said Anne-Marie Weijmans of the University of St Andrews, the survey's Data Products Coordinator. The collaboration is already planning ahead: "We just spent a week talking about what will go into DR21 and DR22! We're going to need bigger computers!" said Juna Kollmeier of Carnegie Science, SDSS-V Director.
