AN ATLAS OF BALMER LINES (H-DELTA AND H-GAMMA)

We obtained spectra for 70 stars of spectral types O to G and luminosi ty classes V, III, and I. They are in the blue between 4000 and 4500 a ngstrom at a resolution of congruent-to 2 angstrom. Our aim is to deri ve pure equivalent widths of Hdelta and Hgamma using a Voigt profile f itting and to plot them as a function of the spectral type. Our result s are compared to theoretical ones issued from the last models of Kuru cz. Moreover, we have measured equivalent widths of blended hydrogen l ines, as it is generally the case in the litterature, and collated the m to those compiled by Tinsley from several authors and those derived by Lennon et al. for supergiant stars. These equivalent widths axe use ful for stellar classification and population synthesis of galaxies (p aper II).