Measured Q/I and U/I parameters and correction for the temporal evolution of the telescope polarization position angle due to the changing parallactic angle during one polarimetric cycle. The blue circle sections show the effect of the changing telescope polarization angle θ_tel during the Q⁺ (lightest blue), Q⁻, U⁺, and U⁻ (darkest blue) integrations. The required corrections for Stokes Q/I and U/I are indicated by the orange and green arrows, respectively.