  The results of the first ever contemporaneous multi-wavelength observation
campaign on the BL Lac object PKS2155-304 involving Swift, NuSTAR, Fermi-LAT
and H.E.S.S. are reported. The use of these instruments allows us to cover a
broad energy range, important for disentangling the different radiative
mechanisms. The source, observed from June 2013 to October 2013, was found in a
low flux state with respect to previous observations but exhibited highly
significant flux variability in the X-rays. The high-energy end of the
synchrotron spectrum can be traced up to 40 keV without significant
contamination by high-energy emission. A one-zone synchrotron self-Compton
model was used to reproduce the broadband flux of the source for all the
observations presented here but failed for previous observations made in April
2013. A lepto-hadronic solution was then explored to explain these earlier
observational results.
