Study of low frequency hydromagnetic waves using ATS-1 data

An analysis was made of ATS-1 data to determine at what point in the magnetic storm recovery phase are oscillations most likely to begin. The catalog of hourly values of equatorial Dst was used to determine the time of main phase decrease, and a catalog of oscillations from January to May 1968 to determine onset time as observed by ATS-1. For each oscillation event at ATS-1, the nearest prior main phase decrease with a magnitude of at least -35 gamma was determined, and the time difference between the onset of the event at ATS-1 and the time of main phase decrease was measured. The resulting data indicate that the most probable time to observe onset of transverse oscillations is within 24 hours after the main phase decrease.