THE intensities of 10 keV and 4 keV electrons have been measured from a sounding rocket launched into a post-breakup aurora. Pulsations in electron intensity were observed with a period of about 4 sec at both energies. The 10 keV pulsations occurred about half a second earlier than those at 4 keV. These results could have been caused by temporal changes in electron intensity and by a spatial structure in the path of the rocket because the causes are indistinguishable in the data. We treat the observed pulsations as temporal changes; they are similar in shape to pulsations observed in auroral light intensity, and electrons in the range 10 keV to 4 keV are important in the production of auroral light. If the pulsations are temporal in origin, the delay can be explained as a dispersion after simultaneous modulation 55,000 km from the rocket. The source of the modulation is found to be near the point where the local magnetic field line crosses the geomagnetic equator.