Evolution of the spectral parameters during the type-I burst, as measured from BAT (first point) and XRT. The bolometric luminosity and the bbodyrad radius are computed by using a distance of 4 kpc. The bottom panel shows the values for all fits. The dashed line in the first upper panel represents the best determined exponential function with which we fit the burst profile. It shows an e-folding time of τ_fit ≈ 55 s.