Siena Galaxy Atlas 2020

TL;DR

The Siena Galaxy Atlas 2020 provides a comprehensive multi-wavelength imaging catalog of over 380,000 nearby galaxies, enabling diverse astrophysical studies and serving as a valuable legacy dataset.

Contribution

It offers an extensive, multi-wavelength imaging atlas of a large galaxy sample with detailed photometry and metadata, enhancing research capabilities beyond previous catalogs.

Findings

High completeness for large galaxies (over 95%)

Provides precise coordinates and multi-wavelength mosaics

Enables new studies of galaxy evolution and local velocity field

Abstract

We present the 2020 version of the Siena Galaxy Atlas (SGA-2020), a multi-wavelength optical and infrared imaging atlas of 383,620 nearby galaxies. The SGA-2020 uses optical $grz$ imaging over $\approx20,000$ deg$^{2}$ from the DESI Legacy Imaging Surveys Data Release 9 and infrared imaging in four bands (spanning 3.4-22 $\mu$m) from the six-year unWISE coadds; it is more than 95% complete for galaxies larger than $R(26)\approx25$ arcsec and $r<18$ measured at the 26 mag arcsec$^{-2}$ isophote in the $r$-band. The atlas delivers precise coordinates, multi-wavelength mosaics, azimuthally averaged optical surface brightness profiles, model images and photometry, and additional ancillary metadata for the full sample. Coupled with existing and forthcoming optical spectroscopy from the Dark Energy Spectroscopic Instrument (DESI), the SGA-2020 will facilitate new detailed studies of the star formation and mass assembly histories of nearby galaxies; enable precise measurements of the local velocity field via the Tully-Fisher and Fundamental Plane relations; serve as a reference sample of lasting legacy value for time-domain and multi-messenger astronomical events; and more.