Figure 13.1: On-board clock-drift analysis for orbit 968, in which no eclipses
occurred and the perigee passage was relatively high. Top graph: the evolution of the drift over the orbit, and the residuals for the spline fit (around
zero) and the harmonic fit (around apogee, offset). Middle graph: The first
derivative of the spline fit to the clock drift, showing the temperature variations, here dominated by the rotation of the satellite. Bottom graph: The
second derivative of the spline fit, showing the heat intake (negative values) or
loss (positive values), depending on the orientation of the satellite. The black
dots refer to data obtained with the Odenwald ground station, the green dots
refer to Goldstone.