Correlation between the BeePRELTH parameter and the PCCS2+2E CIRRUS_N parameter. Sources in the BeeP catalogue were sorted in ascending order of RELTH. Then a boxcar average with window = 500 was calculated for both RELTH and the corresponding PCCS2+2E CIRRUS_N values. The relationship is particularly tight for low values of the parameters, as seen in the expanded detail window, obtained following the exact same procedure as the main picture but using PCCS2 data only. We also reduced the boxcar window to just 50 samples here. The dashed vertical line is the PCCS2 CIRRUS_N reliability threshold.