Absence of hydromagnetic waves in the magnetospheric equatorial region conjugate with pulsating auroras

Magnetic field variations measured by the GOES 2 and 3 satellites are examined at the time when auroras pulsate in their conjugate ionospheric regions. No hydromagnetic waves are found to be related to the pulsating auroras by the satellites. The result indicates that the mechanism leading to pulsating precipitation of electrons, which causes pulsating auroras, does not require the cooperation of hydromagnetic waves in the magnetospheric equatorial region.