Siena Galaxy Atlas 2020

Description

Published by the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys team, the Siena Galaxy Atlas 2020 (SGA-2020) is an atlas of 383,620 nearby galaxies primarily selected from the HyperLeda extragalactic database of known large angular-diameter galaxies. The catalog contains detailed information for these galaxies based on the deep, wide-field grz imaging from LS DR9 and the all-sky infrared imaging at 3.4-22 microns from unWISE, spanning nearly 20,000 square degrees.

The sga2020.tractor table has been crossmatched against our default reference datasets within a 1.5 arcsec radius, nearest neighbor only. These tables will appear with x1p5 in their name in our table browser. Example: sga2020.x1p5__tractor__gaia_dr3__gaia_source.

See the Data Lab table browser for table names and column descriptions in the sga2020 schema.

Note that we have added the following columns to the two data tables to improve usability within Data Lab:

• elon
• elat
• glon
• glat
• htm9
• ring256
• nest4096
• random_id

For a full description of the SGA-2020 release, please visit the Legacy Survey data page (https://www.legacysurvey.org/sga/sga2020/).

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Data Access

The SGA-2020 data are accessible by a variety of means:

Data Lab Table Access Protocol (TAP) service

TAP provides a convenient access layer to the SGA-2020 catalog database. TAP-aware clients (such as TOPCAT) can point to https://datalab.noirlab.edu/tap, select the sga2020 database, and see the database tables and descriptions. You can also view the SGA-2020 tables and descriptions in the Data Lab table browser.

Data Lab Query Client

The Query Client is available as part of the Data Lab software distribution. The Query Client provides a Python API to Data Lab database services. These services include anonymous and authenticated access through synchronous or asynchronous queries of the catalog made directly to the database. Additional Data Lab services for registered users include personal database storage and storage through the Data Lab VOSpace.

The Query Client can be called from a Jupyter Notebook on the Data Lab Notebook server. Example notebooks are provided to users upon creation of their user account (register here), and are also available to browse on GitHub at https://github.com/astro-datalab/notebooks-latest.

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Acknowledgments

Use of the SGA-2020 data products must acknowledge the Scientific Publication Acknowledgment for the DESI Legacy Imaging Surveys as well as the following specific SGA acknowledgment:

The Siena Galaxy Atlas was made possible by funding support from the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0020086 and from the National Science Foundation under grant AST-1616414.

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