Magnetosheath electrons in anomalously low density solar wind observed by Geotail

We present an overview of the magnetosheath electron observations above 60 eV in the anomalously low density solar wind on 11 May 1999 observed by Geo tail. We observed anisotropic 'strahl' component not only in the solar wind but also in the magnetosheath. Strahl, is observed during the interval of 6-21h UT and most enhanced in the interval surrounding the solar wind densi ty minimum in 18-19h UT. Its temperature seems positively correlated to its flux. We also evaluate the density and temperature of low energy isotropic component. The variation of density is associated with proton density. Its temperature is continuous, and suddenly decreased after the density minimu m in similar to 18-19h UT. We also compared our downstream data with upstre am one observed by the ACE spacecraft. We conclude that the electron accele ration and heating at the bow shock is executed in the ordinal mechanisms e ven in the low density solar wind.