The X-ray curve is situated near the top/bottom of the B/C-level. C-flares are very likely, the probability for M-flares is around 20%. The December 7 M1.2 flare (07:29UT peak time) from NOAA AR 1909 was associated with a CME. CACTus determined it as a (partial) halo CME with a speed around 900 km/s.
The bulk of the plasma is ejected under the ecliptic plane. The side of the CME may impact the Earth. This glancing blow can possibly arrive late December 9, early December 10 and may result in geomagnetic disturbances.
Late December 7, a co-rotating interaction region (CIR) arrived. The density increased gradually together with the magnetic field. The z-component fluctuated strongly, even to -25nT which resulted in a planetary K of 6 and 5 and local K Dourbes of 5 and 4 early December 8. Following the density increase and slow decrease, the solar wind speed increased gradually. The CIR and fast solar wind is possibly linked with the coronal hole which reached the central meridian on December 3.
A shock is visible on ACE data on December 8, 7:30UT: the solar wind speed increased from 500 km/s to around 650 km/s, the temperature, density and magnetic field dropped. This fast reverse shock is possibly linked with the filament eruption of December 5. The geomagnetic impact will be limited andsmaller compared to the CIR because of the drop in magnetic field strength. Bz rotated from negative (-5nT).
INFO FROM SIDC
Equipment: Coronado 90 + SBIG 8300s + LX75
Processing: Photoshop
Date: 12/08/13
Time UT: 04:00
Exposure 0.8 sec.
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