2D distribution of the peak power a); peak period b); power variance d); and noise e) in the 304 Å bandpass. The 1D power map as a function of the radius and period c). The asterisk and plus contours mark the cut-off period c) and the reconstructed magnetic inclination f). Panels a) and c) have the same colour table. The dashed lines mark the umbra–penumbra boundary. The region of low significance is cross-hatched.