Alonso Floriano, F. J.Morales, J. C.Caballero, J. A.Montes Gutiérrez, DavidKlutsch, A.Mundt, R.Cortés Contreras, MiriamRibas, I.Reiners, A.Amado, P. J.Quirrenbach, A.Jeffers, S. V.2023-06-182023-06-182015-050004-636110.1051/0004-6361/201525803https://hdl.handle.net/20.500.14352/24160© ESO 2015. CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Científicas (CSIC), the European Union through European Regional Fund (FEDER/ERF), the Spanish Ministry of Economy and Competitiveness, the state of Baden-Wurttemberg, the German Science Foundation (DFG), and the Junta de Andalucía, with additional contributions by the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofísica de Andalucía, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofísica de Canarias, Hamburger Sternwarte, Centro de Astrobiología, and the Centro Astronómico Hispano-Alemán). Financial support was also provided by the Universidad Complutense de Madrid, the Comunidad Autónoma de Madrid, the Spanish Ministerios de Ciencia e Innovación and of Economía y Competitividad, and the Fondo Europeo de Desarrollo Regional (FEDER/ERF) under grants AP2009-0187, SP2009/ESP-1496, AYA2011-30147-C03-01, -02, and -03, AYA2012-39612-C03-01, and ESP2013-48391-C4-1-R. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut fur Astronomie and the Instituto de Astrofísica de Andalucía. This research made use of the SIMBAD, operated at Centre de Données astronomiques de Strasbourg, France, the NASA's Astrophysics Data System, the RECONS project database (http://www.recons.org), the M, L, T, and Y dwarf compendium housed at http://dwarfarchives.org maintained by C. Gelino, J. D. Kirkpatrick and A. Burgasser, and the Washington Double Star Catalog maintained at the US Naval Observatory. We thank S. Lepine and E. Gaidos for sharing unpublished data with us, J. I. González Hernández, E. W. Guenther, A. Hatzes, and M. R. Zapatero Osorio of the CARMENES Consortium for helpful comments, and the anonymous referee for the quick and encouraging report.Context. CARMENES is a stabilised, high-resolution, double-channel spectrograph at the 3.5m Calar Alto telescope. It is optimally designed for radial-velocity surveys of M dwarfs with potentially habitable Earth-mass planets. Aims. We prepare a list of the brightest, single M dwarfs in each spectral subtype observable from the northern hemisphere, from which we will select the best planet-hunting targets for CARMENES. Methods. In this first paper on the preparation of our input catalogue, we compiled a large amount of public data and collected low-resolution optical spectroscopy with CAFOS at the 2.2m Calar Alto telescope for 753 stars. We derived accurate spectral types using a dense grid of standard stars, a double least-squares minimisation technique, and 31 spectral indices previously defined by other authors. Additionally, we quantified surface gravity, metallicity, and chromospheric activity for all the stars in our sample. Results. We calculated spectral types for all 753 stars, of which 305 are new and 448 are revised. We measured pseudo-equivalent widths of H α for all the stars in our sample, concluded that chromospheric activity does not affect spectral typing from our indices, and tabulated 49 stars that had been reported to be young stars in open clusters, moving groups, and stellar associations. Of the 753 stars, two are new subdwarf candidates, three are T Tauri stars, 25 are giants, 44 are K dwarfs, and 679 are M dwarfs. Many of the 261 investigated dwarfs in the range M4.0-8.0V are among the brightest stars known in their spectral subtype. Conclusions. This collection of low-resolution spectroscopic data serves as a candidate target list for the CARMENES survey and can be highly valuable for other radial-velocity surveys of M dwarfs and for studies of cool dwarfs in the solar neighbourhood.engjournal articlehttp://dx.doi.org/10.1051/0004-6361/201525803http://www.aanda.org/open access52Low-mass starsVery-low massProper-motion starsAll-sky surveyStellar kinematic groupsT-tauri starsNearby M-dwarfsMain-sequence starsCastor moving groupVirtual observatory toolsAstrofísicaAstronomía (Física)