Local time variation of Pc-pulsation period at Choutuppal /Hyderabad/, India

From the Pc-micropulsation data recorded at the Choutuppal observatory (Hyderabad), power spectra for successive hours of Pc-regimes over long intervals of time were obtained. Based on the variation of these spectra with time, the nature of the local time dependence of the period of Pc-pulsations has been investigated. The results indicate that on magnetically quiet days, Pc-periods in the 35-45 and 55-65 sec ranges exhibit a U-type diurnal variation (period changing around local noon). The results presented here are relevant to the equatorial region, and have been further discussed in relation to those reported for middle and higher latitudes.