Light curves (left-hand panel) and spectra (middle and right-hand panel) for each GRB in the sample. The light-blue shaded area in the left-hand panels highlights the time interval chosen for the spectral analysis. Middle panels: νF_ν spectra and the best fit model. We note that the data points in the νF_ν panels have been derived for a specific model, and should not be used to perform comparisons with a different model. Right-hand panels: count spectra. In all panels, XRT data are shown in red, BAT in green, GBM-NaI in blue and light-blue, and GBM-BGO in purple.