Single column of the low-resolution 30 (top section), 44 (middle section), and 70 GHz (bottom section) frequency channel covariance matrix, as estimated from 300 LFI DPC FFP10 frequentist simulations (left column); from 300 PR4 prior simulations (middle column); and from 3200 BEYONDPLANCK posterior simulations (right column). The selected column corresponds to the Stokes Q pixel number 100 marked in gray, which is located in the top right quadrant. All covariance matrices are constructed at N_side = 8. Note: the Planck PR4 30 GHz covariance slice has been divided by a factor of 5 and thus it is even stronger than the color scale naively implies.