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.

From DOE, Nov. 20, 2019: Fermilab scientist Antonella Palmese is quoted in this article on scientists’ efforts to get to the bottom of the nature of dark energy. These efforts include the Dark Energy Survey, hosted by Fermilab, and the Dark Energy Spectroscopic Instrument, on which Fermilab scientists are collaborators.

Berkeley Lab’s Dark Energy Spectroscopic Instrument aimed its robotic array of 5,000 fiber-optic “eyes” at the night sky Oct. 22 to capture the first images showing its unique view of galaxy light. It was the first test DESI with its nearly complete complement of components. Fermilab contributed key elements to DESI, including the corrector barrel, hexapod, cage and CCDs. Fermilab also provided the online databases used for data acquisition and the software for the instrument’s robotic positioners.