The energetic (590 keV-1.18 MeV) electron flux data displayed in this site are measured by the DRTS geosynchronous satellite launched by Japan Aerospace Exploration Agency (JAXA) on September 14, 2002. The DRTS satellite is placed at r=6.6 R_E and geographic longitude of 90.75°E.

When substorm occurs, energetic electrons are created and injected into the inner magnetosphere. Once injected, they start to drift eastward around the Earth, resulting that the geosynchronous satellite observes enhancement of electron flux. This feature appeared preferentially on the nightiside and dawnside. In the plot, local midnight and local noon are indicated with filled circle and open circle, respectively.

Details on the DRTS satellite can be found at WWW page of JAXA (http://www.jaxa.jp/projects/sat/drts/index_e.html).