Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
Authors: Blanton Michael R. , Bershady Matthew A. , Abolfathi Bela , Albareti Franco D. , Prieto Carlos Allende , Almeida Andres , Alonso-García Javier , Anders Friedrich , Anderson Scott F. , Andrews Brett , Aquino-Ortíz Erik , Aragón-Salamanca Alfonso , Argudo-Fernández Maria , Armengaud Eric , Aubourg Eric , Avila-Reese Vladimir , Badenes Carles , Bailey Stephen , Barger Kathleen A. , Barrera-Ballesteros Jorge , Bartosz Curtis , Bates Dominic , Baumgarten Falk , Bautista Julian , Beaton Rachael , Beers Timothy C. , Belfiore Francesco , Bender Chad F. , Berlind Andreas A. , Bernardi Mariangela , Beutler Florian , Bird Jonathan C. , Bizyaev Dmitry , Blanc Guillermo A. , Blomqvist Michael , Bolton Adam S. , Boquien Médéric , Borissova Jura , Bosch Remco van den , Bovy Jo , Brandt William N. , Brinkmann Jonathan , Brownstein Joel R. , Bundy Kevin , Burgasser Adam J. , Burtin Etienne , Busca Nicolás G. , Cappellari Michele , Carigi Maria Leticia Delgado , Carlberg Joleen K. , Rosell Aurelio Carnero , Carrera Ricardo , Chanover Nancy J. , Cherinka Brian , Cheung Edmond , Chew Yilen Gómez Maqueo , Chiappini Cristina , Choi Peter Doohyun , Chojnowski Drew , Chuang Chia-Hsun , Chung Haeun , Cirolini Rafael Fernando , Clerc Nicolas , Cohen Roger E. , Comparat Johan , Costa Luiz da , Cousinou Marie-Claude , Covey Kevin , Crane Jeffrey D. , Croft Rupert A. C. , Cruz-Gonzalez Irene , Cuadra Daniel Garrido , Cunha Katia , Damke Guillermo J. , Darling Jeremy , Davies Roger , Dawson Kyle , Macorra Axel de la , Dell’Agli Flavia , Lee Nathan De , Delubac Timothée , Mille Francesco Di , Diamond-Stanic Aleks , Cano-Díaz Mariana , Donor John , Downes Juan José , Drory Niv , Bourboux Hélion du Mas des , Duckworth Christopher J. , Dwelly Tom , Dyer Jamie , Ebelke Garrett , Eigenbrot Arthur D. , Eisenstein Daniel J. , Emsellem Eric , Eracleous Mike , Escoffier Stephanie , Evans Michael L. , Fan Xiaohui , Fernández-Alvar Emma , Fernandez-Trincado J. G. , Feuillet Diane K. , Finoguenov Alexis , Fleming Scott W. , Font-Ribera Andreu , Fredrickson Alexander , Freischlad Gordon , Frinchaboy Peter M. , Fuentes Carla E. , Galbany Lluís , Garcia-Dias R. , García-Hernández D. A. , Gaulme Patrick , Geisler Doug , Gelfand Joseph D. , Gil-Marín Héctor , Gillespie Bruce A. , Goddard Daniel , Gonzalez-Perez Violeta , Grabowski Kathleen , Green Paul J. , Grier Catherine J. , Gunn James E. , Guo Hong , Guy Julien , Hagen Alex , Hahn ChangHoon , Hall Matthew , Harding Paul , Hasselquist Sten , Hawley Suzanne L. , Hearty Fred , Hernández Jonay I. Gonzalez , Ho Shirley , Hogg David W. , Holley-Bockelmann Kelly , Holtzman Jon A. , Holzer Parker H. , Huehnerhoff Joseph , Hutchinson Timothy A. , Hwang Ho Seong , Ibarra-Medel Héctor J. , Ilha Gabriele da Silva , Ivans Inese I. , Ivory KeShawn , Jackson Kelly , Jensen Trey W. , Johnson Jennifer A. , Jones Amy , Jönsson Henrik , Jullo Eric , Kamble Vikrant , Kinemuchi Karen , Kirkby David , Kitaura Francisco-Shu , Klaene Mark , Knapp Gillian R. , Kneib Jean-Paul , Kollmeier Juna A. , Lacerna Ivan , Lane Richard R. , Lang Dustin , Law David R. , Lazarz Daniel , Lee Youngbae , Goff Jean-Marc Le , Liang Fu-Heng , Li Cheng , Li Hongyu , Lian Jianhui , Lima Marcos , Lin Lihwai , Lin Yen-Ting , Lis Sara Bertran de , Liu Chao , Lizaola Miguel Angel C. de Icaza , Long Dan , Lucatello Sara , Lundgren Britt , MacDonald Nicholas K. , Machado Alice Deconto , MacLeod Chelsea L. , Mahadevan Suvrath , Maia Marcio Antonio Geimba , Maiolino Roberto , Majewski Steven R. , Malanushenko Elena , Malanushenko Viktor , Manchado Arturo , Mao Shude , Maraston Claudia , Marques-Chaves Rui , Masseron Thomas , Masters Karen L. , McBride Cameron K. , McDermid Richard M. , McGrath Brianne , McGreer Ian D. , Medina Peña Nicolás , Melendez Matthew , Merloni Andrea , Merrifield Michael R. , Meszaros Szabolcs , Meza Andres , Minchev Ivan , Minniti Dante , Miyaji Takamitsu , More Surhud , Mulchaey John , Müller-Sánchez Francisco , Muna Demitri , Munoz Ricardo R. , Myers Adam D. , Nair Preethi , Nandra Kirpal , Nascimento Janaina Correa do , Negrete Alenka , Ness Melissa , Newman Jeffrey A. , Nichol Robert C. , Nidever David L. , Nitschelm Christian , Ntelis Pierros , O’Connell Julia E. , Oelkers Ryan J. , Oravetz Audrey , Oravetz Daniel , Pace Zach , Padilla Nelson , Palanque-Delabrouille Nathalie , Palicio Pedro Alonso , Pan Kaike , Parejko John K. , Parikh Taniya , Pâris Isabelle , Park Changbom , Patten Alim Y. , Peirani Sebastien , Pellejero-Ibanez Marcos , Penny Samantha , Percival Will J. , Perez-Fournon Ismael , Petitjean Patrick , Pieri Matthew M. , Pinsonneault Marc , Pisani Alice , Poleski Radosław , Prada Francisco , Prakash Abhishek , Queiroz Anna Bárbara de Andrade , Raddick M. Jordan , Raichoor Anand , Rembold Sandro Barboza , Richstein Hannah , Riffel Rogemar A. , Riffel Rogério , Rix Hans-Walter , Robin Annie C. , Rockosi Constance M. , Rodríguez-Torres Sergio , Roman-Lopes A. , Román-Zúñiga Carlos , Rosado Margarita , Ross Ashley J. , Rossi Graziano , Ruan John , Ruggeri Rossana , Rykoff Eli S. , Salazar-Albornoz Salvador , Salvato Mara , Sánchez Ariel G. , Aguado D. S. , Sánchez-Gallego José R. , Santana Felipe A. , Santiago Basílio Xavier , Sayres Conor , Schiavon Ricardo P. , Schimoia Jaderson da Silva , Schlafly Edward F. , Schlegel David J. , Schneider Donald P. , Schultheis Mathias , Schuster William J. , Schwope Axel , Seo Hee-Jong , Shao Zhengyi , Shen Shiyin , Shetrone Matthew , Shull Michael , Simon Joshua D. , Skinner Danielle , Skrutskie M. F. , Slosar Anže , Smith Verne V. , Sobeck Jennifer S. , Sobreira Flavia , Somers Garrett , Souto Diogo , Stark David V. , Stassun Keivan , Stauffer Fritz , Steinmetz Matthias , Storchi-Bergmann Thaisa , Streblyanska Alina , Stringfellow Guy S. , Suárez Genaro , Sun Jing , Suzuki Nao , Szigeti Laszlo , Taghizadeh-Popp Manuchehr , Tang Baitian , Tao Charling , Tayar Jamie , Tembe Mita , Teske Johanna , Thakar Aniruddha R. , Thomas Daniel , Thompson Benjamin A. , Tinker Jeremy L. , Tissera Patricia , Tojeiro Rita , Toledo Hector Hernandez , Torre Sylvain de la , Tremonti Christy , Troup Nicholas W. , Valenzuela Octavio , Valpuesta Inma Martinez , Vargas-González Jaime , Vargas-Magaña Mariana , Vazquez Jose Alberto , Villanova Sandro , Vivek M. , Vogt Nicole , Wake David , Walterbos Rene , Wang Yuting , Weaver Benjamin Alan , Weijmans Anne-Marie , Weinberg David H. , Westfall Kyle B. , Whelan David G. , Wild Vivienne , Wilson John , Wood-Vasey W. M. , Wylezalek Dominika , Xiao Ting , Yan Renbin , Yang Meng , Ybarra Jason E. , Yèche Christophe , Zakamska Nadia , Zamora Olga , Zarrouk Pauline , Zasowski Gail , Zhang Kai , Zhao Gong-Bo , Zheng Zheng , Zheng Zheng , Zhou Xu , Zhou Zhi-Min , Zhu Guangtun B. , Zoccali Manuela , Zou Hu 
Published: June 2017

Abstract
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median

). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between

and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.