Geomagnetic activity on March 5th, 2008 recorded by the Tromsø Geophysical Observatory’s magnetometers at Bear Island (BJN), Nordkapp (NOR), Sørøya (SOR) and Tromsø (TRO). Time is along the horizontal axis, while the measured variation in the horizontal component, as well as geomagnetic latitude, is along the vertical axis, a scale indicating 200 nT is in the bottom left corner. The vertical blue dashed line represents the two datasets used for the study at 18:41:30 UT and 18:42:40 UT.