Flux uncertainties for the 0 degree channel of the Lp-band dataset, plotted against the brightness of the sources in magnitudes. The green points denote sources with reliable polarization parameters as was determined later in the analysis, while the black points indicate sources that were rated as unreliable. The uncertainties were determined from the flux variations in background apertures and can therefore only be regarded as lower limit for the actual uncertainties. The other channels show a very similar uncertainty distribution.