The spectral energy distribution of the nebula and the flaring component C1. The data on the nebula have been compiled in Meyer et al. (2010). Details on the modelling of the synchrotron nebula are provided in that reference as well. In addition to the nebula, the SED of the feature C1 is shown together with a time-dependent model of the flare (solid red line), with spectra calculated at the epoch of the flare maximum (t_f) and one day before (t_f − 1d) and after (t_f + 1d) the maximum.