Coadded spectroscopy of all bursts (except burst # 2) at the maximum photospheric radius. The solid red line is the best-fitting model including the continuum and the emission line, E₁, the absorption lines, E₂ and E₃, and the absorption lines at 2.2 keV (due to the reflectivity of gold M shell of the detector itself). The middle panel shows the residuals of the fitting of the model without lines. The residuals of the best fit model to the data are plotted in the bottom panel.