Simultaneous observations of PKS 2155-304 with HESS, Fermi, RXTE, and atom: spectral energy distributions and variability in a low state - Aharonian, Felix A.; Behera, Bagmeet; Hauser, Marcus; Kaufmann, Sarah; Pedaletti, Giovanna; Quirrenbach, Andreas; Schwemmer, Stephanie; Tam, Pak Hin; Wagner, Stefan (The astrophysical journal. Part 2, Letters, 2009)