M2.1 solar flare, glancing blow shock passage possible

Monday, 21 September 2015 - 13:35 UTC

M2.1 solar flare, glancing blow shock passage possible

Sunspot region 2415 produced an M2.1 solar flare (R1-minor) that peaked yesterday at 18:03 UTC. This solar flare was a long duration event and early imagery from SDO suggested right away that this solar flare was associated with a coronal wave and coronal dimming. Fancy words... yes we know... but these two solar features are classic signs that the solar flare launched a coronal mass ejection.

ALERT: Type II Radio Emission
Begin Time: 2015 Sep 20 1817 UTC
Estimated Velocity: 1358 km/s
SUMMARY: 10cm Radio Burst
Begin Time: 2015 Sep 20 1754 UTC
Maximum Time: 2015 Sep 20 1804 UTC
End Time: 2015 Sep 20 1817 UTC
Duration: 23 minutes
Peak Flux: 320 sfu
Latest Penticton Noon Flux: 110 sfu

SOHO coronagraph imagery showed us straight away that this solar flare launched an impressive coronal mass ejection but the bulk of this coronal mass ejection is heading well west and south of Earth as was to be expected due to sunspot region 2415 it's location near the west limb.

Animations: SOHO LASCO C2 and C3 imagery showing the CME of yesterday's M2.1 solar flare.

Updated coronagraph imagery from SOHO shows a very faint halo outline which is hard to spot but definitely there. The low energy protons and electrons as measured by EPAM also showed a distinct increase. Taking into account the speed of this coronal mass ejection at 1.250km/s (CACtus) to 875km/s (NOAA) we have to conclude that a shock passage will be possible either late on 22 September or early on 23 September.

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