Observations of emission line galaxies. III. The broad Balmer line profiles of 12 Seyfert-1 galaxies.

Spectrophotometric observations of a sample of 12 compact Seyfert-1 galaxies have been obtained with resolutions of 6 Å and 9 Å in the spectral range 3800 - 7250 Å. The high signal to noise ratio of these spectra has allowed to measure the fluxes in the Balmer lines up to H_δ with typical errors of the order of 10% for H_α, H_β, H_γ and 20% for H_δ. A linear correlation between the log[F(H_γ)/F(H_β)]_BC and log[F(H_δ)/F(H_β)]_BC ratios, which nearly corresponds to the galactic reddening line, has been found. The absolute value of the asymmetry index at 20% and 50% intensity level of the H_β broad component was found to be correlated with the [F(H_γ)/F(H_β)]_BC ratio providing a new constraint on future models of the broad emission-line region.