Large-scale electron bombardment of the atmosphere at the sudden commencement of a geomagnetic storm

A burst of X rays was observed at balloon altitude over Alaska with the onset of a sudden commencement geomagnetic storm at 0146 UT on June 27, 1960. The electron bombardment of the upper atmosphere that gave rise to the X rays occurred on a large scale, ionospheric absorption coincident with the X-ray burst being observed by riometers in Alaska, Sweden, and Norway.