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The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation

Hahn, ChangHoon; Wilson, Michael J.; Ruiz-Macias, Omar; Cole, Shaun; Weinberg, David H.; Moustakas, John; Kremin, Anthony; Tinker, Jeremy L.; Smith, Alex; Wechsler, Risa H.; Ahlen, Steven; Alam, Shadab; Bailey, Stephen; Brooks, David; Cooper, Andrew P.; Davis, Tamara M.; Dawson, Kyle; Dey, Arjun; Dey, Biprateep; Eftekharzadeh, Sarah; Eisenstein, Daniel J.; Fanning, Kevin; Forero-Romero, Jaime E.; Frenk, Carlos S.; Gaztañaga, Enrique; A Gontcho, Satya Gontcho; Guy, Julien; Honscheid, Klaus; Ishak, Mustapha; Juneau, Stéphanie; Kehoe, Robert; Kisner, Theodore; Lan, Ting-Wen; Landriau, Martin; Le Guillou, Laurent; Levi, Michael E.; Magneville, Christophe; Martini, Paul; Meisner, Aaron; Myers, Adam D.; Nie, Jundan; Norberg, Peder; Palanque-Delabrouille, Nathalie; Percival, Will J.; Poppett, Claire; Prada, Francisco; Raichoor, Anand; Ross, Ashley J.; Safonova, Sasha; Saulder, Christoph; Schlafly, Eddie; Schlegel, David; Sierra-Porta, David; Tarle, Gregory; Weaver, Benjamin A.; Yèche, Christo...

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ChangHoon Hahn

Omar Ruiz-Macias

David H. Weinberg

John Moustakas

Anthony Kremin

Jeremy L. Tinker

Alex Smith

Risa H. Wechsler

Steven Ahlen

Shadab Alam

Stephen Bailey

David Brooks

Andrew P. Cooper

Tamara M. Davis

Kyle Dawson

Arjun Dey

Biprateep Dey

Sarah Eftekharzadeh

Daniel J. Eisenstein

Kevin Fanning

Jaime E. Forero-Romero

Enrique Gaztañaga

Satya Gontcho A Gontcho

Julien Guy

Klaus Honscheid

Mustapha Ishak

Stéphanie Juneau

Robert Kehoe

Theodore Kisner

Ting-Wen Lan

Martin Landriau

Laurent Le Guillou

Michael E. Levi

Christophe Magneville

Paul Martini

Aaron Meisner

Adam D. Myers

Jundan Nie

Nathalie Palanque-Delabrouille

Will J. Percival

Claire Poppett

Francisco Prada

Anand Raichoor

Ashley J. Ross

Sasha Safonova

Christoph Saulder

Eddie Schlafly

David Schlegel

David Sierra-Porta

Gregory Tarle

Benjamin A. Weaver

Christophe Yèche

Rongpu Zhou

Zhimin Zhou

Hu Zou


Over the next 5 yr, the Dark Energy Spectroscopic Instrument (DESI) will use 10 spectrographs with 5000 fibers on the 4 m Mayall Telescope at Kitt Peak National Observatory to conduct the first Stage IV dark energy galaxy survey. At z < 0.6, the DESI Bright Galaxy Survey (BGS) will produce the most detailed map of the universe during the dark-energy-dominated epoch with redshifts of >10 million galaxies spanning 14,000 deg2. In this work, we present and validate the final BGS target selection and survey design. From the Legacy Surveys, BGS will target an r < 19.5 mag limited sample (BGS Bright), a fainter 19.5 < r < 20.175 color-selected sample (BGS Faint), and a smaller low-z quasar sample. BGS will observe these targets using exposure times scaled to achieve homogeneous completeness and cover the footprint three times. We use observations from the Survey Validation programs conducted prior to the main survey along with simulations to show that BGS can complete its strategy and make optimal use of "bright" time. BGS targets have stellar contamination <1%, and their densities do not depend strongly on imaging properties. BGS Bright will achieve >80% fiber assignment efficiency. Finally, BGS Bright and BGS Faint will achieve >95% redshift success over any observing condition. BGS meets the requirements for an extensive range of scientific applications. BGS will yield the most precise baryon acoustic oscillation and redshift-space distortion measurements at z < 0.4. It presents opportunities for new methods that require highly complete and dense samples (e.g., N-point statistics, multitracers). BGS further provides a powerful tool to study galaxy populations and the relations between galaxies and dark matter.


Hahn, C., Wilson, M. J., Ruiz-Macias, O., Cole, S., Weinberg, D. H., Moustakas, J., …Zou, H. (2023). The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation. Astronomical Journal, 165(6), Article 253.

Journal Article Type Article
Acceptance Date Mar 3, 2023
Online Publication Date May 26, 2023
Publication Date Jun 1, 2023
Deposit Date Nov 1, 2023
Publicly Available Date Nov 1, 2023
Journal The Astronomical Journal
Print ISSN 0004-6256
Electronic ISSN 1538-3881
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 165
Issue 6
Article Number 253
Keywords Space and Planetary Science; Astronomy and Astrophysics
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Copyright Statement
© 2023. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

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