Figure 1: The modulation coefficient M1 as observed over the mission, for the two
fields of view. Most of the discontinuities are the result of refocusing (as indicated
by the grey lines), others are caused by temporary thermal-control problems. The
red dots relate to the preceding, the green dots to the following field of view. These
data are for the centre of each field of view, and for a colour index of (V − I)C = 0.5.