The Target-selection Pipeline for the Dark Energy Spectroscopic Instrument

Full list of authors: Myers, Adam D.; Moustakas, John; Bailey, Stephen; Weaver, Benjamin A.; Cooper, Andrew P.; Forero-Romero, Jaime E.; Abolfathi, Bela; Alexander, David M.; Brooks, David; Chaussidon, Edmond; Chuang, Chia-Hsun; Dawson, Kyle; Dey, Arjun; Dey, Biprateep; Dhungana, Govinda; Doel, Peter; Fanning, Kevin; Gaztanaga, Enrique; Gontcho, Satya Gontcho; Gonzalez-Morales, Alma X.; Hahn, ChangHoon; Herrera-Alcantar, Hiram K.; Honscheid, Klaus; Ishak, Mustapha; Karim, Tanveer; Kirkby, David; Kisner, Theodore; Koposov, Sergey E.; Kremin, Anthony; Lan, Ting-Wen; Landriau, Martin; Lang, Dustin; Levi, Michael E.; Magneville, Christophe; Napolitano, Lucas; Martini, Paul; Meisner, Aaron; Newman, Jeffrey A.; Palanque-Delabrouille, Nathalie; Percival, Will; Poppett, Claire; Prada, Francisco; Raichoor, Anand; Ross, Ashley J.; Schlafly, Edward F.; Schlegel, David; Schubnell, Michael; Tan, Ting; Tarle, Gregory; Wilson, Michael J.; Yeche, Christophe; Zhou, Rongpu; Zhou, Zhimin; Zou, Hu.--This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
In 2021 May, the Dark Energy Spectroscopic Instrument (DESI) began a 5 yr survey of approximately 50 million total extragalactic and Galactic targets. The primary DESI dark-time targets are emission line galaxies, luminous red galaxies, and quasars. In bright time, DESI will focus on two surveys known as the Bright Galaxy Survey and the Milky Way Survey. DESI also observes a selection of "secondary" targets for bespoke science goals. This paper gives an overview of the publicly available pipeline (desitarget) used to process targets for DESI observations. Highlights include details of the different DESI survey targeting phases, the targeting ID (TARGETID) used to define unique targets, the bitmasks used to indicate a particular type of target, the data model and structure of DESI targeting files, and examples of how to access and use the desitarget code base. This paper will also describe "supporting" DESI target classes, such as standard stars, sky locations, and random catalogs that mimic the angular selection function of DESI targets. The DESI target-selection pipeline is complex and sizable; this paper attempts to summarize the most salient information required to understand and work with DESI targeting data. © 2023. The Author(s). Published by the American Astronomical Society.
A.D.M. and J.M. were supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award Numbers DE-SC0019022 and DE-SC0020086. A.P.C. is supported by a Taiwan Ministry of Education Yushan Fellowship and Taiwan Ministry of Science and Technology grant No. 109-2112-M-007-011-MY3. This research is supported by the Director, Office of Science, Office of High Energy Physics of the U.S. Department of Energy under Contract No. DEAC0205CH11231, and by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under the same contract; additional support for DESI is provided by the U.S. National Science Foundation, Division of Astronomical Sciences under Contract No. AST-0950945 to the NSF's National Optical-Infrared Astronomy Research Laboratory; the Science and Technologies Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Science and Technology of Mexico (CONACYT); the Ministry of Science and Innovation of Spain (MICINN), and by the DESI Member Institutions: https://www.desi.lbl.gov/collaborating-institutions.
With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).