Flux density uncertainties (, see Eq. (17), as a percentage) versus NPSNR. Blue contours ([68,95,99]%) show the distribution of uncorrected values (as presented in the catalogue), while red contours show the distribution of values after the corrections suggested in Appendix B.2. Left panel: sources in the PCCS2, middle panel: PCCS2E with Galactic latitude greater than 10°, and right panel: sources close to the Galactic plane, with b ≤ 10°. For reference, we show NPSNR⁻¹ (black dashed line), the theoretical lower boundary for , which can only be achieved if flux density is the sole parameter in the model.