Sky Survey Data Releases 2 Million Stellar Objects

The universe is big, and it’s getting bigger.

To study dark energy, the mysterious force behind the accelerating expansion of our universe, scientists are using the Dark Energy Spectroscopic Instrument (DESI) to map nearly 40 million galaxies, quasars and stars. Today, the collaboration publicly released its first batch of data, with nearly 2 million objects for researchers to explore.

The 80-terabyte data set comes from 2,480 exposures taken over six months during the experiment’s “survey validation” phase in 2020 and 2021. Between turning the instrument on and beginning the official science run, researchers made sure their plan for using the telescope would meet their science goals—for example, by checking how long it took to observe galaxies of different brightness, and by validating the selection of stars and galaxies to observe.

“The fact that DESI works so well, and that the amount of science-grade data it took during survey validation is comparable to previous completed sky surveys, is a monumental achievement,” said Nathalie Palanque-Delabrouille, co-spokesperson for DESI and a scientist at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), which manages the experiment. “This milestone shows that DESI is a unique spectroscopic factory whose data will not only allow the study of dark energy but will also be coveted by the whole scientific community to address other topics, such as dark matter, gravitational lensing and galactic morphology.”

Kyle Dawson

DESI uses 5,000 robotic positioners to move optical fibers that capture light from objects millions or billions of light-years away. It is the most powerful multi-object survey spectrograph in the world, able to measure light from more than 100,000 galaxies in one night. That light tells researchers how far away an object is, building a 3-D cosmic map.

“This new sample represents the first science-quality data taken with this powerful new instrument. These survey-validation data are better quality and provide spectra and classification of a wider range of stars, galaxies and quasars than the data we expect in the main five-year program,” said Professor Kyle Dawson. Dawson of the University of Utah was one of the two primary leads of the survey validation effort and is also DESI co-spokesperson.  “We have learned from these data how to build the most effective cosmology program.”

Read the entire article in @TheU.