The authors thank Molly Swanson for her great work and help on MANGLE. HC is supported by Conselho Nacional de Desenvolvimento Cient´ıfico e Tecnologico (CNPq). AC thanks Fer- ´ nando de Simoni for useful discussions. AC acknowledges financial support provided by the Programa de Apoio ao Pos-Doutorado ´ (PAPDRJ)/Coordenac¸ao de Aperfeic ˜ ¸oamento de Pessoal de N´ıvel Superior (CAPES)/Fundac¸ao de Amparo ˜ a Pesquisa do Estado do ` Rio de Janeiro (FAPER) Fellowship. ML is partially supported by Fundac¸ao de Amparo ˜ a Pesquisa do Estado de S ` ao Paulo (FAPESP) ˜ and CNPq. FBA acknowledges the support of the Royal society via a RS University Research Fellowship. FS acknowledges financial support provided by CAPES under contract No. 3171-13-2. JC and FP acknowledge support from the Spanish Ministerio de Ciencia e Innovacion (MICINN) grant MultiDark CSD2009-00064, Ministe- ´ rio de Econom´ıa, Industria y Competitividad (MINECO) Severo Ochoa Programme grant SEV-2012-0249 and grant AYA2014- 60641-C2-1-P. FP wish to thank the Lawrence Berkeley National Laboratory for the hospitality and the Spanish MEC Salvador de Madariaga program, Ref. PRX14/00444. This paper has gone through internal review by the DES collaboration. We are grateful for the extraordinary contributions of our CTIO colleagues and the DECam Construction, Commissioning and Science Verification teams in achieving the excellent instrument and telescope conditions that have made this work possible. The success of this project also relies critically on the expertise and dedication of the DES Data Management group. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundaca o Carlos Chagas Filho de Amparo a Pesquisa do ` Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cient´ıfico e Tecnologico and the Miniserio da Ciencia e Tecnolo- ´ gia, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey. The DES data management system is supported by the National Science Foundation under Grant Number AST1138766. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA201239559, ESP2013-48274, FPA2013-47986, and Centro de Excelencia Severo Ochoa SEV2012-0234, some of which include ERDF funds from the European Union. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the Eidgenssische Technische Hochschule (ETH) Zurich, Fermi National Accelerator Laboratory, the University of Edinburgh, the University of Illinois at Urbana-Champaign, the Institut de Ciencies de lEspai ` (IEEC/CSIC), the Institut de F´ısica dAltes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universitt and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex and Texas A&M University. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for HighPerformance Computing at the University of Utah. The SDSS web site is www.sdss.org. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrof´ısica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut fur Astrophysik ¨ Potsdam (AIP), Max-Planck-Institut fur Astronomie (MPIA Hei- ¨ delberg), Max-Planck-Institut fur Astrophysik (MPA Garching), ¨ Max-Planck-Institut fur Extraterrestrische Physik (MPE), National ¨ Astronomical Observatory of China, New Mexico State University, New York University, University of Notre Dame, Observatario Na- ´ cional/MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autonoma de M ´ exico, Uni- ´ versity of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University and Yale University

We present the results of the first observations of the emission line galaxies (ELG) of the extended Baryon Oscillation Spectroscopic Survey. From the total 9000 targets, 4600 have been selected from the Dark Energy Survey (DES). In this subsample, the total success rate for redshifts between 0.6 and 1.2 is 71 and 68 per cent for a bright and a faint samples, respectively, including redshifts measured from a single strong emission line. The mean redshift is 0.80 for the bright and 0.87 for the faint sample, while the percentage of unknown redshifts is 15 and 13 per cent, respectively. In both cases, the star contamination is lower than 2 per cent. We evaluate how well the ELG redshifts are measured using the target selection photometry and validating with the spectroscopic redshifts measured by eBOSS. We explore different techniques to reduce the photometric redshift outliers fraction with a comparison between the template fitting, the neural networks and the random forest methods. Finally, we study the clustering properties of the DES SVA1 ELG samples. We select only the most secure spectroscopic redshift in the redshift range 0.6 < z < 1.2, leading to a mean redshift for the bright and faint sample of 0.85 and 0.90, respectively. We measure the projected angular correlation function and obtain a galaxy bias averaging on scales from 1 to 10 Mpc h of 1.58 ± 0.10 for the bright sample and 1.65 ± 0.12 for the faint sample. These values are representative of a galaxy population with M - log(h) < -20.5, in agreement with what we measure by fitting galaxy templates to the photometric data. © 2017 The Authors

Jouvel, S. et al.-- Full list of authors: Jouvel, S.; Delubac, T.; Comparat, J.; Camacho, H.; Carnero, A.; Abdalla, F. B.; Kneib, J. -P.; Merson, A.; Lima, M.; Sobreira, F.; da Costa, Luiz; Prada, F.; Zhu, G. B.; Benoit-Levy, A.; De La Macora, A.; Kuropatkin, N.; Lin, H.; Abbott, T. M. C.; Allam, S.; Banerji, M.; Bertin, E.; Brooks, D.; Capozzi, D.; Kind, M. Carrasco; Carretero, J.; Castander, F. J.; Cunha, C. E.; Desai, S.; Doel, P.; Eifler, T. F.; Estrada, J.; Neto, A. Fausti; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Lahav, O.; Li, T. S.; Maia, M. A. G.; March, M.; Marshall, J. L.; Miquel, R.; Ogando, R.; Percival, W. J.; Plazas, A. A.; Reil, K.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Santiago, B.; Scarpine, V.; Sevilla-Noarbe, I.; Soares-Santos, M.; Suchyta, E.; Tarle, G.; Thaler, J.; Thomas, D.; Walker, A.; Zhang, Y.; Brownstein, J.