06/21/2015 15:30:00 UTC

Comment Section

• Compound event with a series of shocks arriving over a 3-day span, and one likely magnetic cloud arriving around midnight on the 23rd, corresponding to a clear, symmetric halo CME on the 21st which drove the strongest of the shocks with a highly compressed magnetic field. Drove a powerful geomagnetic storm with a Dst near -200 (Hess)