The Siena Galaxy Atlas (SGA) is a compilation of data from three surveys completed between 2014 and 2017 known as the DESI Legacy Surveys, which were carried out to identify galaxy targets for the Dark Energy Spectroscopic Instrument (DESI) survey. The data were collected at Cerro Tololo Inter-American Observatory and Kitt Peak National Observatory, both Programs of NSF’s NOIRLab, and at the University of Arizona’s Steward Observatory. The atlas also contains data from a survey by NASA’s Wide-field Infrared Survey Explorer (WISE) satellite.
“Nearby large galaxies are important because we can study them in more detail than any other galaxies in the Universe; they are our cosmic neighbors,” said Siena College’s Professor John Moustakas, SGA project leader.
“Not only are they strikingly beautiful, but they also hold the key to understanding how galaxies form and evolve, including our very own Milky Way Galaxy.”
The new atlas builds on several centuries of efforts to chart the night skies.
The iconic Catalogue des Nébuleuses et des Amas d’Étoiles (Catalogue of Nebulae and Star Clusters), published in 1774 by French astronomer Charles Messier, was a major milestone, as was the New General Catalogue of Nebulae and Clusters of Stars (NGC), published in 1888 by John Louis Emil Dreyer.
More recently, in 1991, astronomers assembled the Third Reference Catalog of Bright Galaxies (RC3).
Several other valuable galaxy atlases have been published over the past two decades, but most of them draw on the photographic-plate measurements in the RC3, or are missing significant numbers of galaxies.
Since the SGA uses digital images captured with highly sensitive instruments, it represents a substantial improvement in both data quality and completeness.
“Previous galaxy compilations have been plagued by incorrect positions, sizes and shapes of galaxies, and also contained entries which were not galaxies but stars or artifacts,” said Dr. Arjun Dey, an…
Read the full article here