Single column of the low-resolution CMB noise covariance matrix, as estimated by the LFI DPC (top row) and BEYONDPLANCK (bottom row). The column corresponds to the Stokes Q pixel marked in gray, which is located in the top right quadrant near the ‘Q’ label. We note that the DPC covariance matrix is constructed at N_side = 16 and includes a cosine apodization filter, while the BEYONDPLANCK matrix is constructed at N_side = 8 with no additional filter.