SIMBAD references

In this paper, the continuum emission of active galactic nuclei is studied using broadband B, V, R, and I photometry. The nuclear contribution is estimated from the observations using two different approaches. In the first one, the images are deconvolved by the seeing profile and the corrected images are used to derive the nuclear contribution. In the second method, in order to extract the stellar contribution, a de Vaucouleurs brightness profile is assumed for the bulge. After subtraction of this component, the total nuclear emission is obtained from the corrected image. Both methods indicate that the stellar contribution is dominant. The average contribution of the featureless continuum to the total observed continuum is 30% in the four bands. We show that over 2 orders of magnitude the Hα emission-line luminosity correlates with the continuum emission in all the observed bands. As a consequence, the galaxies in the sample must have similar color index. This result provides a method to estimate the reddening correction for the nuclear continuum, which we found to be lower than the emission-line extinction correction estimated from the observed Hα/Hβ observed line ratio.