Comparison of the VLT/X-shooter spectrum and the synthetic model. The VLT/X-shooter spectrum (black line) de-reddened by E_B − V = 1.25 is compared with the synthetic model (magenta) corresponding to the following atmospheric parameters: T_eff = 3500 K, log g = 0.0, [M/H] = 0.0, and [α/H] = 0.0. The residuals – observations minus calculations – are shown at the bottom with gray line. The spectra were normalized to the flux level at the narrow range (50 Å) centered at 22 155 Å. The scale factor is S_f = F_obs/F_model = 7.7 × 10⁻¹⁹.