GRB 151027A rate light curve (middle panel). The Fermi-GBM NaI(0) data (8 keV–1 MeV) are shown by the green line. The Swift-BAT (15–150 keV) light curve is shown by the red line. The rescaled Swift-XRT (0.3–10 keV) light curve is shown by the blue line. Vertical dashed lines represent the start and stop times of the intervals selected for the spectral analysis. Top panels: νF_ν spectra of the rise (left, #1) and decay (middle, #2) phase of the first peak and of the second peak (right, #3), corresponding to the first three hatched regions in the middle panel. Green and red symbols show the GBM and BAT data, respectively, and the solid line is the best fit model (see Table 2). Bottom panels: νF_ν spectra of the third peak corresponding to the shaded regions of the light curve (middle panel, #4-#7). The blue symbols show the XRT spectra. The two model components (cutoff power law and blackbody) are shown by the dashed lines and their sum by the solid line.