Dark energy instrument’s lenses see the night sky for the first time

The Dark Energy Spectroscopic Instrument seeks to further our cosmic understanding by creating the largest 3-D map of galaxies to date. Below is a press release issued by Lawrence Berkeley National Laboratory announcing first light for the optical lenses of this extraordinary instrument. The U.S. Department of Energy’s Fermi National Accelerator Laboratory is a key player in the construction of this instrument, drawing on more than 25 years of experience with the Sloan Digital Sky Survey and the Dark Energy Survey.

Fermilab contributed key elements to DESI, including the corrector barrel, hexapod and cage. The corrector barrel – designed, built and initially tested at Fermilab – aligns DESI’s six large lenses to within the accuracy of the width of a human hair. This precision is essential to ensure that the images DESI collects are sharp and clear. The hexapod, designed and built with partners in Italy, moves and focuses the lenses. Both the barrel and hexapod are housed in the cage, which was also designed and built by Fermilab. Additionally, Fermilab carried out the testing and packaging of the charge-coupled devices, or CCDs. The CCDs convert the light passing through these lenses from distant galaxies into digital information that can then be analyzed by the collaboration.

Read more in the press release here.

DESI “first light” image of the Whirlpool Galaxy, also known as Messier 51. This image was obtained the first night of observing with the DESI Commissioning Instrument on the Mayall Telescope at the Kitt Peak National Observatory in Tucson, Arizona; an r-band filter was used to capture the red light from the galaxy. Image: DESI collaboration