On August 27th, 1998 at 10:22 UT the Earth was hit by an intense shower of gamma rays which originated some 23,000 light years distant with the colossal shake up of a highly magnetic neutron star called a magnetar. Details about this event can be seen at several locations, but my favorite is the press release by the HAIL VLF array.
SARA member, Eulif Robison, has been running a magnetometer for several months and has contributed the following graphs collected over a period which covered that day. Unfortunately, the Earth was already being hit by a blast of solar wind particles on the day when the gamma ray event occured. Typical, quiet days in the earths magnetic field can be seen above and below the chart for the 27th. Thus it is hard to be sure that the feature which occurs at 10:22 on the chart is really related to the gamma ray event. Still, it is worthwhile we believe to post this data here for comparisons by others who may have been making magnetic measurements on that day. The 27th is the third graph down from the top. The UT appears along the top of the chart.