Differential variation (the closer to the right the points are, the closer they are to the serial register) of the normalized third moment, γ, as a function of flux (averaged peak flux of the comb lines in log scale). The range of the left part of the detector goes from the first to the 2048th pixel along the dispersion direction on detectors. The right part of the detector goes from 2048th to the 4096th pixel. Operator E stands for the averaged value for each side on the chip. The dashed red line is an exponential fit to the data points.