Moderate M1.2 solar flare erupted around AR 1909


Moderate solar flare measuring M1.2 erupted today from around AR 1909. The event started at 07:17, peaked at 07:29 and ended at 07:49 UTC. Region 1909 (S17W50, Dso/beta) is decreasing in size but maintains some magnetic complexity.

A 10 cm Radio Burst lasting 4 minutes with peak flux of 220 sfu was associated with the event. A 10 cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10 cm wavelength was double or greater than the initial 10 cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.

A Type II Radio Emission was also registered:

ALERT: Type II Radio Emission
Begin Time: 2013 Dec 07 0723 UTC
Estimated Velocity: 691 km/s
Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.


SUMMARY: 10cm Radio Burst
Begin Time: 2013 Dec 07 0721 UTC
Maximum Time: 2013 Dec 07 0722 UTC
End Time: 2013 Dec 07 0725 UTC
Duration: 4 minutes
Peak Flux: 220 sfu
Latest Penticton Noon Flux: 151 sfu

The CME associated with the filament that erupted near Region 1909 on December 5 was analyzed and the resulting Enlil model run suggests that a weak glancing blow is possible on December 8 but conditions will likely be dominated by high speed wind effects at that time. CME is expected at 05:46 UTC (+/- 6 hours).


There are currently 6 numbered sunspot regions on the disk. While southern hemisphere is peppered with sunspots, none of them is strongly flaring. Region 1916 (S13W10, Dac/beta-gamma) showed moderate growth in its intermediate and trailer spots but only produced a pair of optical flares in last 36 hours.

Sunspots on December 7, 2013. 

1908 S25W79 236 40 2 HSX 2 Alpha
1909 S17W50 207 140 10 DSO 10 Beta
1911 S11W64 221 10 1 AXX 1 Alpha
1912 S21E17 140 130 14 CAO 1 Beta
1915 S30W48 206 30 8 DRO 10 Beta
1916 S13W10 168 200 9 DAC 21 Beta-Gamma

Solar activity is expected to be low with a slight chance for M-class (NOAA Scale R1-R2, Minor-Moderate) flares for the next three days (December 7 – 9).

Solar wind speeds are expected to increase on December 7 with the onset of a recurrent positive polarity coronal hole high speed stream (CH HSS) and remain elevated during December 8. A gradual decrease is expected on December 9 as CH HSS effects subside.

The geomagnetic field is expected to be unsettled to active with a slight chance for an isolated minor storm period on December 7  due to CH HSS effects as well as on December 8 due to a combination of CH HSS effects and possible weak influence from the CME associated with the December 5 filament eruption.

A return to quiet conditions is expected on December 9 as effects subside.

Featured image: NASA SDO/AIA 304

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