Mapping the night sky is essential for understanding our universe. Both researchers and amateur astronomers can now access a new atlas with detailed information on more than 380,000 galaxies: the Siena Galaxy Atlas (SGA). The collection, which provides precise measurements of the locations, shapes, and sizes of large nearby galaxies, promises to be a boon to future astronomical inquiry and is freely accessible online for all to use. The research was published today in the Astrophysical Journal Supplements.

The Siena Galaxy Atlas compiles data from three surveys completed between 2014 and 2017 known as the DESI Legacy Surveys. These observations were carried out to identify galaxy targets for the Dark Energy Spectroscopic Instrument (DESI), an international project managed by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). Data were collected at Cerro Tololo Inter-American Observatory (CTIO) and Kitt Peak National Observatory (KPNO), both Programs of NSF’s NOIRLab, and the University of Arizona’s Steward Observatory.

“The light from large, nearby galaxies can confuse our view of the distant universe, which we need to measure to understand and explain dark energy – the mystery force that is accelerating the expansion of our universe,” said David Schlegel, a researcher in Berkeley Lab’s Physics Division and the co-lead of one of the DESI Legacy Surveys. “So one goal with the atlas was to catalog, model, and – where possible – subtract the light of these nearby galaxies from our DESI observations, and it’s been very successful. In making this atlas, we also got a detailed view of nearby galaxies, which is useful in other ways.”

The surveys captured images in optical and infrared wavelengths to chart a total area of 20,000 square degrees — nearly half of the night sky, making it among the largest galaxy surveys. Besides the sheer number of objects recorded, the data in the SGA also achieves a new level of accuracy and is the first such resource to provide data on the galaxies’ light profiles.

Read the full article:
New Map of Space Precisely Measures Nearly 400,000 Nearby Galaxies
October 18, 2023 / Lauren Biron / Berkeley Lab News Center