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One of magnetic pulsations occur during a geomagnetic storm is Pc5 magnetic pulsation. Previous studies have shown that Pc5 pulsations are triggered by the solar wind, therefore, it can be used to estimate solar wind parameters and are related to geomagnetic disturbance. In this study, the presence of Pc5 magnetic pulsation during the onset of the geomagnetic storm is identified and analyzed using local geomagnetic data. The aim is to determine the relationship between the time of Pc5 pulsation presence and geomagnetic storm onset. The results acquired by using Jayapura's geomagnetic data in the 2015 geomagnetic storms show that for all SSC-type storms, Pc5 pulsations preceded storm onset in the range of 8 minutes to 1 hour, while for GS types, Pc5 magnetic pulses did not always precede storm onset. Pc5 maximum amplitude generally occured before the peak of the storm and ranged from 0.6-15 nT.