The Astronomical Journal (Jan 2023)

The Target-selection Pipeline for the Dark Energy Spectroscopic Instrument

  • Adam D. Myers,
  • John Moustakas,
  • Stephen Bailey,
  • Benjamin A. Weaver,
  • Andrew P. Cooper,
  • Jaime E. Forero-Romero,
  • Bela Abolfathi,
  • David M. Alexander,
  • David Brooks,
  • Edmond Chaussidon,
  • Chia-Hsun Chuang,
  • Kyle Dawson,
  • Arjun Dey,
  • Biprateep Dey,
  • Govinda Dhungana,
  • Peter Doel,
  • Kevin Fanning,
  • Enrique Gaztañaga,
  • Satya Gontcho A Gontcho,
  • Alma X. Gonzalez-Morales,
  • ChangHoon Hahn,
  • Hiram K. Herrera-Alcantar,
  • Klaus Honscheid,
  • Mustapha Ishak,
  • Tanveer Karim,
  • David Kirkby,
  • Theodore Kisner,
  • Sergey E. Koposov,
  • Anthony Kremin,
  • Ting-Wen Lan,
  • Martin Landriau,
  • Dustin Lang,
  • Michael E. Levi,
  • Christophe Magneville,
  • Lucas Napolitano,
  • Paul Martini,
  • Aaron Meisner,
  • Jeffrey A. Newman,
  • Nathalie Palanque-Delabrouille,
  • Will Percival,
  • Claire Poppett,
  • Francisco Prada,
  • Anand Raichoor,
  • Ashley J. Ross,
  • Edward F. Schlafly,
  • David Schlegel,
  • Michael Schubnell,
  • Ting Tan,
  • Gregory Tarle,
  • Michael J. Wilson,
  • Christophe Yèche,
  • Rongpu Zhou,
  • Zhimin Zhou,
  • Hu Zou

DOI
https://doi.org/10.3847/1538-3881/aca5f9
Journal volume & issue
Vol. 165, no. 2
p. 50

Abstract

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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.

Keywords