  We present detailed broadband UV/optical to X-ray spectral variability of the
Seyfert 1 galaxy 1H 0419-577 using six XMM-Newton observations performed during
2002-2003. These observations covered a large amplitude variability event in
which the soft X-ray (0.3-2 keV) count rate increased by a factor of ~4 in six
months. The X-ray spectra during the variability are well described by a model
consisting of a primary power law, blurred and distant reflection. The 2-10 keV
power-law flux varied by a factor ~7 while the 0.3-2 keV soft X-ray excess flux
derived from the blurred reflection component varied only by a factor of ~2.
The variability event was also observed in the optical and UV bands but the
variability amplitudes were only at the 6-10% level. The variations in the
optical and UV bands appear to follow the variations in the X-ray band. During
the rising phase, the optical bands appear to lag behind the UV band but during
the declining phase, the optical bands appear to lead the UV band. Such
behavior is not expected in the reprocessing models where the optical/UV
emission is the result of reprocessing of X-ray emission in the accretion disc.
The delayed contribution of the broad emission lines in the UV band or the
changes in the accretion disc/corona geometry combined with X-ray reprocessing
may give rise to the observed behavior of the variations.

High Energy Astrophysical Phenomena