Detected ME arcs for perijoves 1 through 54, shown in red, overlain on the pixelwise median-average aurora for each hemisphere. A 15°-by-15° grid in System-III longitude and planetocentric latitude is overlain on the aurora. The System-III longitude of certain gridlines are given in white, and the planetocentric latitudes of certain gridlines in magenta. The brightness scale of the images of the aurora in kR is given at the bottom of (b). A histogram of the distribution of detected ME arcs in both local time (top) and System-III longitude (bottom) is given for both the northern and southern hemispheres.