DESI

A telescope on a hill on a starry night

The first batch of data from the Dark Energy Spectroscopic Instrument is now available for researchers to mine. Taken during the experiment’s “survey validation” phase, the data include distant galaxies and quasars as well as stars in our own Milky Way.

A tessellated image of a white cap with a blue dot on the right edge, with shadow surrounding. This image is tessellated many times. A single cap, center right, is different: It has a white dot with a white concentric circle around it on top. No blue.

DESI will capture and study the light from tens of millions of galaxies and other distant objects to better understand our universe and the properties of dark energy. The formal start of DESI’s five-year survey follows a four-month trial run of its custom instrumentation that captured 4-million spectra of galaxies — more than the combined output of all previous spectroscopic surveys. Fermilab has contributed multiple components to the international collaboration led by Berkeley Lab.

Scientists have begun operating the Dark Energy Spectroscopic Instrument, or DESI, to create a 3-D map of over 30 million galaxies and quasars that will help them understand the nature of dark energy. The new instrument is the most advanced of its kind, with 5,000 robotic positioners that will enable scientists to gather more than 20 times more data than previous surveys. Researchers at Fermilab helped develop the software that will direct these positioners to focus on galaxies several billion light-years away and are currently in the process of fine-tuning the programs used before the last round of testing later this year.