  In this work, the analysis of multi-epoch (1995-2010) X-ray observations of
the Seyfert 1 galaxy H0557-385 is presented. The wealth of data presented in
this analysis show that the source exhibits dramatic spectral variability, from
a typical unabsorbed Seyfert 1 type spectrum to a Compton-thin absorbed state,
on time scales of ~5 years. This extreme change in spectral shape can be
attributed to variations in the column density and covering fraction of a
neutral absorbing medium attenuating the emission from the central continuum
source. Evidence for Compton reflection of the intrinsic nuclear emission is
present in each of the spectra, though this feature is most prominent in the
low-state spectra, where the associated Fe emission line complex is clearly
visible. In addition to the variable absorbing medium, a warm absorber
component has been detected in each spectral state. Optical spectroscopy
concurrent with the 2010 XMM-Newton observation campaign have detected the
presence of broad optical emission lines during an X-ray absorption event.From
the analysis of both X-ray and optical spectroscopic data, it has been inferred
that the X-ray spectral variability is a result of obscuration of the central
emission region by a clumpy absorber covering >80 per cent of the source with
an average column density of NH ~7x10^{23} cm^{-2}, and which is located
outside the broad line region at a distance from the central source consistent
with the dust sublimation radius of the AGN.
