  The High Energy Stereoscopic System (H.E.S.S.) has observed the
high-frequency peaked BL Lac object PKS2155-304 in 2003 between October 19 and
November 26 in Very High Energy (VHE) gamma-rays (E>160 GeV for these
observations). Observations were carried out simultaneously with the
Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer
satellite (RXTE), the Robotic Optical Transient Search Experiment (ROTSE) and
the Nancay decimetric radiotelescope (NRT). Intra-night variability is seen in
the VHE band, the source being detected with a high significance on each night
it was observed. Variability is also found in the X-ray and optical bands on
kilosecond timescales, along with flux-dependent spectral changes in the
X-rays. The average H.E.S.S. spectrum shows a very soft power law shape with a
photon index of 3.37+/-0.07(stat)+/-0.10(sys). The energy outputs in the 2-10
keV and in the VHE gamma-ray range are found to be similar, with the X-rays and
the optical fluxes at a level comparable to some of the lowest historical
measurements, indicating that PKS2155-304 was in a low or quiescent state
during the observations. Both a leptonic and a hadronic model are used to
derive source parameters from these observations.
