Time-resolved spectroscopy using the NS atmosphere model in addition to the f_a correction for burst #4. Results for other bursts are shown in Fig. A.4. Blue markers are used for the first f_a case, constant*(diskbb+comptt) and light green markers for the second f_a case, constant*diskbb+comptt. Since their behavior is similar, the blue markers overlap the green ones. Panel a shows the estimated bolometric flux, panel b shows the time evolution of the ratio of luminosity to Eddington luminosity, panel c shows the evolution of the f_a factor, and panel d gives the reduced χ² fit statistic.