Evolution of the kT component of the BB+PL model during episode 1. The first data point corresponds to 5 s before the first BAT trigger time. The vertical line corresponds to the trigger time. The time is given in the observer frame. The temperature evolves in time following a broken power-law fit. There is a break at t = 41.21 s. The indices of the PL are α = 0 (consistent with a constant function) and β =  −4 ± 2. The presence of the BB, although weaker than in previous cases, is essential to obtain an acceptable fit.