Abstract. The magnetic eld experiment o n A CE provides continuous measurements of the local magnetic eld in the interplanetary medium. These measurements are essential in the interpretation of simultaneous ACE observations of energetic and thermal particles distributions. The experiment consists of a pair of twin, boommounted, triaxial uxgate sensors which are located 165 inches = 4.19 meters from the center of the spacecraft on opposing solar panels. The electronics and digital processing unit DPU is mounted on the top deck of the spacecraft. The two triaxial sensors provide a balanced, fully redundant v ector instrument and permit some enhanced assessment of the spacecraft's magnetic eld. The instrument provides data for Browse and high-level products with between 3 and 6 vector s ,1 resolution for continuous coverage of the interplanetary magnetic eld. Two highresolution snapshot bu ers each hold 297 seconds of 24 vector s ,1 data while onboard Fast Fourier Transforms extend the continuous data to 12 Hz resolution. Real-time observations with 1 second resolution are provided continuously to the Space Environmental Center SEC of the National Oceanographic and Atmospheric Association NOAA for near-instantaneous, world-wide dissemination in service to space weather studies. As has been our team's tradition, high instrument reliability is obtained by the use of fully redundant systems and extremely conservative designs. We plan studies of the interplanetary medium in support of the fundamental goals of the ACE mission and cooperative studies with other ACE investigators using the combined ACE dataset as well as other ISTP spacecraft involved in the general program of Sun-Earth Connections.

No abstract

No abstract

No abstract

No abstract

No abstract

Measurements of the flux and energy spectrum of electrons, incident at the top of the atmosphere at Fort Churchill, Manitoba, exhibit a large daily intensity variation in the energy interval from about 10 to 225 Mev. High intensities are observed during the day, low intensities at night. No such variation is noticed at higher energies. This result is interpreted to be a consequence of the asymmetry of the geomagnetic field. We conclude, on the basis of our interpretation, that the high electron flux observed during the day in the low‐energy interval is mainly due to return albedo particles. These return albedo particles are not observed at night. The lower flux at night is interpreted as an upper limit to the flux of primary electrons of energy between about 20 and 250 Mev, which amounts to 81±20 electrons/m² sec ster.

No abstract