Final Targeting Strategy for the SDSS-IV APOGEE-2N Survey
Creators: name: Beaton, Rachael L.
name: Oelkers, Ryan J.
name: Hayes, Christian R.
name: Covey, Kevin R.
name: Chojnowski, S. D.
name: De Lee, Nathan
name: Sobeck, Jennifer S.
name: Majewski, Steven R.
name: Cohen, Roger
name: Fernandez-Trincado, Jose
name: Longa-Pena, Penelope
name: O'Connell, Julia E.
name: Santana, Felipe A.
name: Stringfellow, Guy S.
name: Zasowski, Gail
name: Aerts, Conny
name: Anguiano, Borja
name: Bender, Chad
name: Canas, Caleb I.
name: Cunha, Katia
name: Fleming, John Donor Scott W.
name: Frinchaboy, Peter M.
name: Feuillet, Diane
name: Harding, Paul
name: Hasselquist, Sten
name: Holtzman, Jon
name: Johnson, Jennifer A.
name: Kollmeier, Juna A.
name: Kounkel, Marina
name: Mahadevan, Suvrath
name: Price-Whelan, Adrian. M.
name: Rojas-Arriagada, Alvaro
name: Roman-Zuniga, Carlos
name: Schlafly, Edward F.
name: Schultheis, Mathias
name: Shetrone, Matthew
name: Simon, Joshua D.
name: Stassun, Keivan G.
name: Stutz, Amelia M.
name: Tayar, Jamie
name: Teske, Johanna
name: Tkachenko, Andrew
name: Troup, Nick
name: Albareti, Franco D.
name: Bizyaev, Dmitry
name: Bovy, Jo
name: Burgasser, Adam J.
name: Comparat, Johan
name: Downes, Juan Jose
name: Geisler, Doug
name: Inno, Laura
name: Manchado, Arturo
name: Ness, Melissa K.
name: Pinsonneault, Marc H.
name: Prada, Francisco
name: Roman-Lopes, Alexandre
name: Simonian, Gregory V. A.
name: Smith, Verne V.
name: Yan, Renbin
name: Zamora, Olga
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: APOGEE-2 is a dual-hemisphere, near-infrared (NIR), spectroscopic survey with the goal of producing a chemo-dynamical mapping of the Milky Way Galaxy. The targeting for APOGEE-2 is complex and has evolved with time. In this paper, we present the updates and additions to the initial targeting strategy for APOGEE-2N presented in Zasowski et al. (2017). These modifications come in two implementation modes: (i) "Ancillary Science Programs" competitively awarded to SDSS-IV PIs through proposal calls in 2015 and 2017 for the pursuit of new scientific avenues outside the main survey, and (ii) an effective 1.5-year expansion of the survey, known as the Bright Time Extension, made possible through accrued efficiency gains over the first years of the APOGEE-2N project. For the 23 distinct ancillary programs, we provide descriptions of the scientific aims, target selection, and how to identify these targets within the APOGEE-2 sample. The Bright Time Extension permitted changes to the main survey strategy, the inclusion of new programs in response to scientific discoveries or to exploit major new datasets not available at the outset of the survey design, and expansions of existing programs to enhance their scientific success and reach. After describing the motivations, implementation, and assessment of these programs, we also leave a summary of lessons learned from nearly a decade of APOGEE-1 and APOGEE-2 survey operations. A companion paper, Santana et al. (submitted), provides a complementary presentation of targeting modifications relevant to APOGEE-2 operations in the Southern Hemisphere.
description: 59 pages; 11 Figures; 7 Tables; 2 Appendices; Submitted to Journal and Under Review; Posting to accompany papers using the SDSS-IV/APOGEE-2 Data Release 17 scheduled for December 2021