Solar activity summary (Last 24 hours)

17 December


Solar activity was low. The largest event of the period was a C3 flare
that occurred at 16/2133 UTC. This event was associated with a 16° long
eruptive prominence on the limb (EPL), centered near S36W90. The
resulting coronal mass ejection (CME) was analyzed and determined to be
directed too far to the west to have any major impacts on the Earth.
Newly numbered Region 1928 (S16E16, Dao/beta-gamma) exhibited fairly
rapid growth throughout the period while displaying prominent mixing
within its magnetic structure. The other regions on the disk were either
stable or indicating minor decay. No Earth-directed CMEs were detected
in imagery.

16 December


Solar activity was low. Region 1917 (S15W44, Ekc/beta-gamma) produced a
C3/Sf flare at 16/0330 UTC, which was the largest event of the period.
Newly-numbered Region 1927 (S25W67, Cao/beta) developed rapidly
overnight while Region 1917 continued to exhibit minor growth. The
other regions on the disk were either stable or undergoing minor decay.
No Earth-directed coronal mass ejections (CMEs) were observed.

15 December


Solar activity was low. The largest event of the period was a C2 flare
at 15/0913 UTC which appeared to be associated with a filament eruption
centered near S25W50. Region 1917 (S15W31, Dkc/beta-gamma) continued to
exhibit growth in both area and magnetic complexity throughout the
period. The other regions on the visible disk were either stable or
undergoing slight decay. No Earth-directed coronal mass ejections
(CMEs) were observed.

14 December


Solar activity was low. Region 1917 (S14W18, Dkc/beta-gamma) produced a
C2/Sf flare at 14/1124 UTC, which was the largest event of the period.
Region 1920 (N11E08, Hax/alpha) and 1925 (S08E47, Cro/beta) each
produced C1 flares at 13/2258 UTC and 14/0940 UTC, respectively. Region
1917 continued to exhibit overall growth throughout the period while the
other regions on the visible disk were either stable or undergoing
slight decay. A 15-degree eruptive prominence was observed on SDO/AIA
304 imagery at around 14/0900 UTC, and was centered near S25W72.
Further analysis is needed to determine if a coronal mass ejection (CME)
associated with the prominence eruption would be Earth-directed.

13 December


Solar activity was low. Region 1921 (N06E29, Cko/Beta) produced a C5/Sf
flare at 12/2214 UTC, which was the largest event of the period. Region
1917 (S15W03, Dao/beta-gamma) produced a C4 flare at 13/0315 UTC and
exhibited slight growth throughout the period, both in overall size and
magnetic complexity. New Region 1925 (S09E62, Cro/beta) was numbered
this period. The other regions on the visible disk were either stable
or exhibited slight decay. No Earth-directed coronal mass ejections
(CMEs) were observed this period.

12 December


Solar activity was low. Region 1916 (S13W85, Hax/alpha) began the period
as the most active spot group, producing a couple of C1 flares. Region
1917 (S15E12, Dao/beta-gamma) then produced a C2/Sf flare at 11/2306
UTC, as well as a long duration C3 flare at 12/0659 UTC. Region 1912
(S21W55, Hax/alpha) decided to finish out the period on an active note,
producing a C4/Sf flare at 12/0336 UTC. A type-II radio sweep estimated
at 511 km/s and a type-IV radio sweep were also observed in conjunction
with this event, as well as several discreet radio bursts at different
frequencies.

There was a 15 degree filament, centered near S31W41, that was observed
in SDO/AIA 304 imagery lifting off the solar disk from 12/0304 UTC to
12/0330 UTC. The resulting partial halo coronal mass ejection (CME) can
first be seen in Lasco C3 imagery at 12/0618 UTC. But, with a large data
gap, the CME appears to have already traveled well away from the solar
disk by the time the first image appears. A current Enlil model run has
been submitted, using the limited data available, and results will be
analyzed to determine if there is a Earthward component to the CME.

A second CME was observed in LASCO C2 imagery at 12/0636 UTC departing
the solar disk with a southerly trajectory. This CME is associated with
a 7 degree filament that departed the solar disk from 12/0451 UTC to
12/0624 UTC and was centered near S32E27. An additional Enlil run may be
accomplished as more data becomes available, though initial analysis
indicates the ejecta was directed too far southward to have any major
impacts on the Earth.

11 December


Solar activity has been at low levels for the past 24 hours. Region 1916
(S12W64, Ekc/beta-gamma) was the most active region on the visible disk.
It produced the largest event of the period, a C2 flare, observed at
10/2007 UTC, as well as several sub-faint flares. New Region 1924
(S13W52, Dro/beta) was numbered today. An approximately 20 degree long
filament, centered near S39E28, was observed in SDO/AIA 304 imagery
erupting from the solar disk from 11/0510 UTC – 11/0810 UTC. The
associated coronal mass ejection (CME) first observed in Lasco C2
imagery at 11/0748 UTC and STEREO COR2 imagery at 11/0809 UTC, indicated
the majority of the ejecta had a nearly straight southward trajectory.
Initial indications suggest a near miss for the Earth. There were no
Earth-directed CMEs detected in satellite imagery during the reporting
period.

10 December


Solar activity was at low levels. Region 1921 (N06E68, Hax/alpha)
produced the largest solar event of the period, a C2 flare, observed at
09/1656 UTC. This region has shown slight growth in overall areal
coverage but remains magnetically simple. Region 1920 (N12E63,
Hax/alpha) also produced a C2 flare, at approximately 09/1321 UTC.
Region 1916 (S12W58, Ekc/beta-gamma) was the most magnetically complex
region on the solar disk, showed the most growth, yet only produced low
level sub-faint flares. The other numbered regions were either stable or
exhibited signs of slight decay. No Earth-directed coronal mass
ejections (CMEs) were observed in satellite imagery during the period.

9 December


Solar activity continued to be at low levels with only minor C-class
flaring observed during the period. Slight growth was observed in
Regions 1917 (S17E50, Dai/beta-gamma) and 1918 (S08E69, Dao/beta-delta)
while the rest of the spotted regions were relatively stable. No
Earth-directed coronal mass ejections (CMEs) were observed during the
period.

8 December


Solar activity was at low levels. Only low level C-class flares were
observed. Slight growth was observed in the intermediate and trailing
spots of Regions 1916 (S13W30, Dac/beta-gamma) and 1917 (S16E64,
Dai/beta). The rest of the spotted regions were either stable or in
decay. No Earth-directed coronal mass ejections (CMEs) were observed
during the period.