Title: Primary electron influx to dayside auroral oval
Abstract: Data from the Ogo 4 auroral particles experiment were analyzed to determine properties of the higher latitude region of electron precipitation in the dayside hemisphere. From 7 months of data a probability map of occurrence of this structured low-energy precipitation was compiled. The highest probabilities are concentrated predominantly between 0500 and 1400 hours magnetic local time, and from 75° to 82½° invariant latitude. There is excellent congruity of these high probabilities of occurrence and the high probability of occurrence of discrete auroral optical emissions, which define the auroral oval in these hours. The soft energy spectrums measured and the estimated total energy influx during typical precipitation events are appropriate for producing the type of aurora observed in these hours. It is concluded that the structured low-energy electron precipitation is the primary energy source for the dayside auroral oval.