  Thermal reverberation in accretion discs of active galactic nuclei is thought
to be the reason of the continuum UV/optical time lags seen in these sources.
Recently, we studied thermal reverberation of a standard Novikov-Thorne
accretion disc illuminated by an X-ray point-like source, and we derived an
analytic prescription for the time lags as function of wavelength. In this
work, we use this analytic function to fit the time-lags spectra of seven
Seyferts, that have been intensively monitored, in many wave-bands, in the last
few years. We find that thermal reverberation can explain the observed
UV/optical time lags in all these sources. Contrary to previous claims, the
magnitude of the observed UV/optical time-lags is exactly as expected in the
case of a standard accretion disc in the lamp-post geometry, given the black
hole mass and the accretion rate estimates for the objects we study. We derive
estimates of the disc accretion rates and corona height for a non-spinning and
a maximally spinning black hole scenarios. We also find that the modelling of
the continuum optical/UV time-lags can be used to estimate the black hole spin,
when combined with additional information. We also find that the model
under-predicts the observed X-ray to UV time-lags, but this difference is
probably due to the broad X-ray auto-correlation function of these sources.
