Cylindrical Stokes-I power spectra ratio after DD calibration (top) and GPR foreground removal (bottom) of the flanking field to the NCP field. The dashed lines, from bottom to top, correspond to the 5° (primary beam), 20°, and 90° (instrumental horizon) delay lines from the phase centre. Red indicates excess power from the flanking field and blue indicates excess power from the NCP field. Some bad data are flagged at the bottom. From top to bottom, the residual foregrounds below the 20° delay line (i.e. excess power from the flanking field) are largely removed after GPR foreground removal.