Distance-time plot for CorPITA EUV wave (black points) and 0.25 s time resolution radio source (green points) with errors for each highlighted by shaded regions. The purple region (P1) highlights the region when the radio source initially travelled at a higher velocity, later slowing in the blue-shaded region (P2) once it reached the region of lower density. These correspond to the same emission marked in Fig. 2. The velocity of the EUV wave was 500 km s⁻¹ and the radio source velocities were 1700 km s⁻¹ and 250 km s⁻¹.