Observations of Jovian Electrons at 1 AU

It has recently been suggested that electrons of Jovian origin are responsible for the 'quiet time increases' in the > 3-MeV electron intensity observed at I AU. Using data from the California Institute of Technology electron/isotope spectrometers on Imp 7 and 8, we have studied the temporal behavior of quiet ime electrons at I AU over the period October 1972 through May 1975. We find the lto 6-MeV electron intensity to vary by a factor of • l0 from one quiet time period to another, including numerous short-term enhancements characteristic of the quiet time increases reported during 1964-1972. The magnitude and frequency of the increases grow abruptly and remain high for a •4-month period beginning with the time at which the interplanetary field line first connects earth and Jupiter. It is suggested that the interconnection f the interplanetary field with an extended Jovian magnetotail of42 AU in length could result in the observed longitudinal distribution of Jovian electrons at I AU.