Kinematics of the reconstructed shock wave. The three axes of an ellipsoidal fit, namely, the shock apex (red) and the two flank axes (r-axis 1 in blue and r-axis 2 in green), are plotted together and represented with different colours. The left and right panels show the height-time evolution of all three shock axes and its first derivative (velocity), respectively. The possible errors are in each axis and indicated by the shaded regions. The ‘+’ and ‘x’ markings on the curves are the constraints provided by the observations.