Over the centuries, catalogs of various galaxies and other cosmic objects have been published. Now, thanks to digital technology, we have a new publicly accessible archive of hundreds of thousands of galaxies close to the Milky Way. This archive can be used for both scientific research and entertainment.
Astronomers at NOIRLab in Tucson, Arizona, have created a digital catalog of nearly 400,000 galaxies, giving scientists and the general public the opportunity to explore the star-filled giants of our galaxy's cosmic neighborhood. Siena Galaxy Atlas 2020 provides a downloadable data model for offline use and an online viewer for browser-based space exploration.
The Siena Galaxy Atlas (SGA) is a compilation of data collected from three sky surveys (known as the DESI Heritage Survey) conducted between 2014 and 2017:
https://www.legacysurvey.org/viewer/#NGC%207529
The data were collected at CerroTololo Inter-American Observatory and Kitt Peak National Observatory (both observatories are part of the NOIRLab program) and the University of Arizona's Stewart Observatory.
The survey captured images at optical and infrared wavelengths covering a total area of 20,000 square inches, nearly half of the night sky. According to NOIRLab, the new digital atlas is one of the largest galaxy surveys ever conducted, providing "precise data" on the positions, shapes and sizes of hundreds of thousands of nearby large galaxies. SGA's data have unprecedented accuracy and are the first resource to provide "light profile" information on galaxies.
According to John Moustakas, professor of physics at Siena College and leader of the SGA project, nearby large galaxies are important because they are "our cosmic neighbors." We can study them in more detail than other galaxies in the universe because they are key to understanding how galaxies form and evolve.
Throughout the history of astronomy and science, many "star maps" of the night sky have been drawn and published, including the iconic Catalog des Nébuleuse set des Amas d'Étoiles by Charles Messier (1774) and the New General Catalog of Nebulae and Star Clusters (NGC) by John Louis Emil Dreyer (1888). In 1991, astronomers compiled the Third Reference Catalog of Bright Galaxies (RC3), which became the basis for other galaxy atlases published in recent years.
The purpose of the Siena Galaxy Atlas is to resolve problems that have plagued previous surveys, including incorrect locations, sizes, and shapes of galaxies, and stars and artifacts being incorrectly cataloged. According to NOIRLab astronomer Arjun Dey, SGA corrects these inaccuracies in "most of the sky" and it also provides "the best measurement of galaxy brightness" for a sample of this size.