The sun unleashed its strongest solar flare in nearly five years on Feb 15, 2011, sending a massive wave of charged particles toward Earth. The Coronal Mass Ejection (CME), a huge cloud of charged particles, reached the earth in approximately 3 days triggering a sizeable geomagnetic storm and a deep Forbush decrease (Fd). Fd is a rapid decrease in observed galactic cosmic ray intensity following a CME arrival. A variety of cosmic ray particle detectors at the Aragats Space Environmental Center (ASEC) in Armenia and the Space Environmental Viewing and Analysis Network (SEVAN), a worldwide network, registered the Fd in minute detail.
For more information on the Cosmic Ray Division visit www.crdfriends.org.