Free Astronomy Magazine May-June 2021

26 data release (DR1), and also im- proves on it by refining calibration techniques, which, with the deeper combined images from DR2, leads to improved estimates of the amount and distribution of matter in the Universe. It is one of the largest astronomical catalogs re- leased to date. Astronomical researchers around the world can access these unprece- dented data and mine them to make new discoveries about the Universe, complementary to the studies being carried out by the Dark Energy Survey collaboration. One early result relates to the con- struction of a catalog of RR Lyrae pulsating stars, which tell scientists about the region of space beyond the edge of our Milky Way. In this area nearly devoid of stars, the mo- Shining a new light on dark energy D R2 is the second release of im- ages and object catalogs from the Dark Energy Survey (DES). It is the culmination of over half a decade of astronomical data collec- tion and analysis, with the ultimate goal of understanding the acceler- ating expansion rate of the Universe and the phenomenon of dark en- ergy that is thought to be responsi- ble for the expansion. The Dark Energy Survey is a global collabora- tion that includes the Department of Energy’s (DOE) Fermi National Accelerator Laboratory (Fermilab), the National Center for Supercom- puting Applications (NCSA), and NSF’s NOIRLab. Including a catalog of nearly 700 million astronomical objects, DR2 builds on the 400 million objects cataloged with the Survey’s previous by NOIRLab - Amanda Kocz T his image shows unusual structures around NGC 474 characterized as tidal tails and shell-like structures made up of hundreds of millions of stars. These features are due to recent mergers (within the last billion years) or close interac- tions with smaller infalling dwarf galaxies. This image is an excerpt from the Dark Energy Survey, which has released a massive, public collection of astro- nomical data and calibrated images from six years of work. [DES/DOE/Fermilab/ NCSA & CTIO/NOIRLab/NSF/AURA - Ack: Image processing: DES, Jen Miller (Gem- ini Observatory/NSF's NOIRLab), Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin]