Refraction shoulders for the five strongly lensing test planets. The y-axis is logarithmic for visual clarity. Blue is the reference Jupiter and is identical to the blue line in Fig. 2. Red is the Earth, yellow is the 80-day super-Earth, green is the 80-day Jovian, and magenta is the best-case Jovian planet. The reference time is set to when the planet centre crosses the star limb, which is equivalent to the second vertical line in Fig. 2.