Median-averaged expansion of the southern ME relative to the UVS reference oval vs. the expansion of the Io, Europa, and Ganymede auroral footprints relative to their magnetically mapped contours at 900 km. The expansion of the Io footprint is denoted by green triangles, that of the Europa footprint by blue circles, and that of the Ganymede footprint by orange squares. The fitted relation between the Io-footprint expansion and the ME expansion is denoted by a green dashed line, that between the Europa-footprint location and the ME expansion by a blue dotted line, and that between the Ganymede-footprint location and the ME expansion by an orange dot-dashed line. The forms and R-squared goodness-of-fit coefficients of these relations are given in the legend. Cases at similar System-III longitudes have been annotated and highlighted with red circles.