Spectral energy distribution of 1RXS J101015.9 − 311909. The H.E.S.S. spectrum is represented by the green bow-tie at the highest energies. The measured Fermi/LAT spectrum above 1 GeV is represented by the orange full bow-tie, while the binned spectral points or upper limits are shown with empty circles (see Sect. 3.1 for details). The Swift/XRT spectrum in case A is shown with green diamonds, while case B is represented with pink crosses. NED database archival data are shown with grey asterisks, while the grey cross represents the flux measured by the SUMSS radio survey (see Sect. 1). Swift/UVOT data are shown with light-red stars; atom data are shown with light-blue squares. Deabsorbed infrared-to-UV data are plotted for case B only to avoid cluttering. The total SSC emission model (including absorption by the EBL) in case A is represented by the solid line, while the modelling in case B is represented by the dashed line. The intrinsic emission models (corrected for EBL absorption) are presented by the thinner lines at higher VHE flux. A template of a spectrum of a giant elliptical galaxy is also shown in the plot by the dashed purple line in the optical range.