PSD slope index (top) and timescales (bottom) estimated from the SF of the total intensity (left) and polarized intensity (right) 2017 and 2018 light curves, for the spectral bands B1 (blue dots) and B4 (orange squares). A second characteristic PSD and timescale, derived from the Stokes I SF, are marked with a cross (x). PSD values are computed from the SF slope as α_PSD = −(1 + α_SF) (blue dots and orange squares for the spectral bands B1 and B4, respectively), and from the HPF periodogram (red triangles and green diamonds for the spectral bands B1 and B4, respectively; see Appendix G).