Variability in the observed Stokes parameters q and u for HD 165052 in the B, V, and R passbands (top two, middle two, and bottom two panels, respectively), phase-folded with the orbital period, 2.95510 d. The dotted (dashed) Fourier fit curves and data points represented with circles (squares) show the data obtained in 2012 (2023). Best-fit Fourier coefficients for the two datasets are given in Table 4. The lengths of the bars correspond to ±σ errors.