Simultaneous observations of pks 2155-304 with HESS, fermi, rxte, and atom: Spectral energy distributions and variability in a low state - Aharonian, F.; Akhperjanian, A.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A.; Becherini, Y.; Behera, B.; Bernlöhr, K.; Boisson, C.; Bochow, A.; Borrel, V.; Brion, E.; et al. (Institute of Physics Publishing, 2009)