  We study the extensively monitored Seyfert galaxy NGC 5548 and compare its
nuclear emission with models of accretion disk with accreting corona. To obtain
the intrinsic nuclear spectra from the observed spectra we had to estimate and
subtract the contribution from circumnuclear components such as stars, the
Balmer continuum and blended FeII lines, and the FC2 extended, featureless
continuum. The true nuclear spectra were compared with a two parameter model of
the accreting disk with an accreting corona, described by the mass of the
central black hole and viscosity. The model that best fitted the data was for
M_{BH}=1.4e8 solar masses and the viscosity parameter alpha=0.033. Such a low
viscosity parameter was necessary to produce the sufficient amount of X-rays.
The vertical outflow of mass from corona in the form of wind had to be
neglected in our model in order to fit into high and low states that NGC 5548
underwent. The model also predicts the behavior of the overall opt/UV/X
continuum of NGC 5548 during the whole five year campaign.
