Figure 12.15: The colour coefficients in the photometric calibration model for the
DC and AC photometry as obtained in the preceding field of view. From top to
bottom: the linear, quadratic and third order terms. In the top two graphs the
upper curve and in the bottom graph the lower curve refers to the AC photometry.
The grey lines show the instances of refocusing of the instrument, events that, as
could be expected, did not affect the colour coefficients.