Multi-wavelength afterglow light curves (see Sect. 3). For each band, the light curves predicted by the standard model with v_sa = 13 GHz, v_m = 6 GHz, v_c = 2 × 10⁷ GHz, F_m = 800 μJy, and p = 2.05 at 1 day for a homogeneous surrounding medium are shown: 1.5 GHz (orange); 5 GHz (blue); r, g, i, and z bands (red, lime, violet, and brown, respectively); integrated X-ray light curve (dark blue). The green, orange, and brown vertical lines pinpoint the epochs of the spectra at 0.12, 1.41, and 23 days, respectively (see also Fig. 3). The dashed line shows a simple model for the SN contribution in the r band (see Sect. 5.1).