Left panel: calculated synchrotron spectrum for electrons accelerated in the bow shock. Spectra were calculated for two sets of the mass-loss rate and the terminal wind velocity that are within the range of values expected from the stellar model: ṁ_w = 5 × 10^-9M_⊙ yr^-1, v_w = 10 km s^-1 and ṁ_w = 10^-8M_⊙ yr^-1, v_w = 100 km s^-1. Solid lines correspond to the plowing synchrotron model and the dashed lines to the local model. The energy spectrum of accelerated electrons has a power-law index of p = 2.4 in accordance with particle-in-cell simulations of Sa¸dowski et al. (2013). The red points are observationally determined values adopted from Davies et al. (1976), Falcke & Markoff (2000), Zhao et al. (2003), and Marrone et al. (2008). The shaded region represents an estimate of the radio flux density of the PWN. Right panel: a synthetic light curve calculated at 1.4 GHz considering for both the plowing (solid lines) and the local model (dashed lines). Two sets of stellar parameters were considered as in the left panel.