High resolution spectroscopy over lambda lambda 8500-8750 angstrom for GAIA I. Mapping the MKK classification system

We present an Echelle+CCD high resolution spectroscopic atlas (0.25 Angstro m/pix dispersion, 0.43 Angstrom FWHM resolution and 20 000 resolving power) mapping the MKK classification system over the interval lambda lambda 8500 - 8750 Angstrom. The wavelength interval is remarkably free from telluric lines and it is centered on the near-IR triplet of Ca II, the head of hydro gen Paschen series and several strong metallic lines. The spectra of 131 st ars of types between O4 and M8 and luminosity classes I through V are inclu ded in the atlas. Special care was put in maintaining the highest instrumen tal homogeneity over the whole set of data. The capability to derive accura te MKK spectral types from high resolution observations over the interval l ambda lambda 8500 - 8750 Angstrom is discussed. The observations have been performed as part of an evaluation study of possible spectroscopic performa nces for the astrometric mission GAIA planned by ESA.