Overview of the DESI Milky Way Survey
Creators: name: Cooper, Andrew P.
name: Koposov, Sergey E.
name: Prieto, Carlos Allende
name: Manser, Christopher J.
name: Kizhuprakkat, Namitha
name: Myers, Adam D.
name: Dey, Arjun
name: Gaensicke, Boris T.
name: Li, Ting S.
name: Rockosi, Constance
name: Valluri, Monica
name: Najita, Joan
name: Deason, Alis
name: Raichoor, Anand
name: Wang, Mei-Yu
name: Ting, Yuan-Sen
name: Kim, Bokyoung
name: Carrillo, Andreia
name: Wang, Wenting
name: Silva, Leandro Beraldo e
name: Han, Jiwon Jesse
name: Ding, Jiani
name: Sanchez-Conde, Miguel
name: Aguilar, Jessica N.
name: Ahlen, Steven
name: Bailey, Stephen
name: Belokurov, Vasily
name: Brooks, David
name: Cunha, Katia
name: Dawson, Kyle
name: de la Macorra, Axel
name: Doel, Peter
name: Eisenstein, Daniel J.
name: Fagrelius, Parker
name: Fanning, Kevin
name: Font-Ribera, Andreu
name: Forero-Romero, Jaime E.
name: Gaztanaga, Enrique
name: Gontcho, Satya Gontcho A
name: Guy, Julien
name: Honscheid, Klaus
name: Kehoe, Robert
name: Kisner, Theodore
name: Kremin, Anthony
name: Landriau, Martin
name: Levi, Michael E.
name: Martini, Paul
name: Meisner, Aaron M.
name: Miquel, Ramon
name: Moustakas, John
name: Nie, Jundan
name: Palanque-Delabrouille, Nathalie
name: Percival, Will J.
name: Poppett, Claire
name: Prada, Francisco
name: Rehemtulla, Nabeel
name: Schlafly, Edward
name: Schlegel, David
name: Schubnell, Michael
name: Sharples, Ray M.
name: Tarle, Gregory
name: Wechsler, Risa H.
name: Weinberg, David H.
name: Zhou, Zhimin
name: Zou, Hu
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We describe the Milky Way Survey (MWS) that will be undertaken with the Dark Energy Spectroscopic Instrument (DESI) on the Mayall 4m telescope at the Kitt Peak National Observatory. Over the next 5 yr DESI MWS will observe approximately seven million stars at Galactic latitudes |b|&gt;20 degrees, with an inclusive target selection scheme focused on the thick disk and stellar halo. MWS will also include several high-completeness samples of rare stellar types, including white dwarfs, low-mass stars within 100pc of the Sun, and horizontal branch stars. We summarize the potential of DESI to advance understanding of Galactic structure and stellar evolution. We introduce the final definitions of the main MWS target classes and estimate the number of stars in each class that will be observed. We describe our pipelines for deriving radial velocities, atmospheric parameters, and chemical abundances. We use ~500,000 spectra of unique stellar targets from the DESI Survey Validation program (SV) to demonstrate that our pipelines can measure radial velocities to ~1 km/s and [Fe/H] accurate to ~0.2 dex for typical stars in our main sample. We find the stellar parameter distributions from ~100 sq. deg of SV observations with &gt;90% completeness on our main sample are in good agreement with expectations from mock catalogs and previous surveys.
description: Accepted for publication in ApJ, 44 pages, 25 figures, 4 tables, one of a suite of 8 papers detailing targeting for DESI; v2 added links to data shown in figures, added citations to other DESI papers, corrected author list and minor typos; v3 fixed minor errors in Fig. 6 and clarified associated text; v4 updated to include minor changes in response to review