Example of a fit to the decay phase of a bolometric light curve of a burst. This is the same burst as in Fig. 2. The top panel shows in logarithmic scale the bolometric flux and the best-fit models for an exponential decay (dashed curve; Eq. (1)), the power law (blue curve; Eq. (2)), and the power-law plus Gaussian function (red curve; Eq. (3)). The second, third, and fourth panels show the residuals with respect to models following Eqs. (1)–(3). The power-law plus Gaussian function is the best model.