Example of the calibration (red lines) of the bias non-uniformity (black dots) after a flush. Three groups of datapoints are evident: the lowest, corresponding to the maximum bias excursion, is the first pixel after the transition from flush to read; the middle and upper are the second and third pixels, respectively. The excursion depends strongly on how many flushes precede it (the horizontal axis), with the effect saturating after ~ 200 flushed pixels. The upwards excursion above the calibration line after 400 pixels is, in this particular case, the glitch caused by the pause in the serial readout.