A year's worth of observations of kilometric continuum (KC) from the plasma wave instrument (PWI) on GEOTAIL and extreme ultraviolet (EUV) images of the plasmasphere from IMAGE are compared. In the vast majority (~94%) of the 87 cases when simultaneous data from both spacecraft were available, KC was observed to be associated with density depletions or notch structures in the plasmasphere. From a careful analysis of 1 month of EUV data comprising 13 notch structures, only one notch structure was found in which no accompanying KC was observed when GEOTAIL was in a low-latitude position and therefore should have observed the emission if it were generated. IMAGE observations from the radio plasma imager (RPI) during passage through a plasmaspheric notch structure found that KC was generated in or very near the magnetic equator at steep gradients in density and associated with emissions in the upper hybrid resonance band as previously reported by others at lower frequencies. Statistical analysis of the KC events associated with plasmaspheric notch structures shows that the typical source region is at an equatorial radial distance of ~2.4 RE (Earth radii) in the magnetic equator and produces an emission cone that is ~40¿ in longitude and ~20¿ in latitude. These results show that a density depletion or notch structure in the plasmasphere is typically a critical condition for the generation of KC but that the notch structures do not always provide the conditions necessary for the generation of the emission.