SolarHam.com | Geomagnetic Sudden Impulse - Sunday SEPTEMBER 30. 2012

The ground based magnetometer located in Boulder, Colorado just detected somewhat of a deviation. This could signal the passage of an interplanetary shock past Earth.

SUMMARY: Geomagnetic Sudden Impulse
Observed: 2012 Sep 30 1138 UTC
Deviation: 15 nT
Station: Boulder