Solar activity summary (Last 24 hours)

28th October


Solar activity reached high levels when Region 1875 (N07W71,
Fkc/beta-gamma-delta) produced an X1/2N flare at 28/0203 UTC. A Type II
radio emission (451 km/s) was reported at 28/0200 UTC. This event was
followed by an asymmetric halo CME first visible in SOHO/LASCO C2
imagery at 28/0224 UTC. A coarse fit using only SOHO/LASCO C3 imagery
and a preliminary WSA-Enlil model run suggests arrival of ejecta on 30
October. However, the lack of sufficient STEREO COR2 imagery for the
fit means confidence in this solution is low and analysis is ongoing.

An M5/2B from the same region followed at 28/0441 UTC and was
accompanied by a Type II radio emission (508 km/S) at 28/0437 UTC, a
Type IV emission, and a 170 sfu Tenflare at 28/0438 UTC. A CME was
subsequently observed in SOHO/LASCO C2 imagery at 28/0448 UTC. Analysis
of this event suggests the ejecta was directed well westward and the
geoeffective potential low.

Over the past 24 hours, Regions 1875 and 1877 have decreased in area and
1877 lost its delta magnetic configuration. Region 1882 (S09E41,
Dkc/beta-gamma-delta) was relatively stable, losing a few spots but
retaining its beta-gamma-delta configuration. Region 1884 (S14E60,
Dao/beta-gamma-delta) and the remaining regions were relatively stable.
Emerging flux was observed near S15E22 and was being monitored.

27th October


Solar activity was at moderate levels. A 27 degree long filament,
centered near S41W32, erupted between 26/0950 – 1310 UTC. LASCO C2
imagery observed a CME at 26/1325 UTC off the SW limb. Newly numbered
Region 1884 (S14E74, Hsx/alpha) produced an M3/Sf flare at 26/1927 UTC
and Region 1882 (S08E27, Dkc/beta-gamma-delta) produced an M1/Sf flare
(R1 Radio Blackout) at 26/1953 UTC. A CME was observed in SOHO/LASCO C2
imagery emerging from the east limb beginning at 26/1912 UTC. A
preliminary analysis suggests the ejecta is moving at about 970 km/s.

At least five other CMEs were observed in C2 imagery exiting the west
limb over the past 24 hours. Examination of SDO/AIA 304 imagery
indicates Regions 1873 (N13W83, Hrx/alpha) and 1875 (N06W56,
Ekc/beta-gamma-delta) as the origin. Where sufficient coronagraph
imagery was available, analysis suggests these events are directed
mostly westward with a slim chance of a significant impact at Earth.
Further analysis will be accomplished when additional STEREO COR2
imagery becomes available.

While Regions 1875 and 1877 (S13W35, Dhi/beta-gamma) remained the
largest spot groups on the visible disk, they only produced a few
C-class flares and changed little over the period. In addition to
Region 1884, two other regions were numbered during the period, Regions
1883 (N04E66, Hsx/alpha) and 1885 (S18E69, Hsx/alpha). Region 1885
appeared to be the origin of an eruption in the southeast visible in
SDO/AIA 304 imagery around 27/0451 UTC.

26th October


Solar activity was high. At 25/1503 UTC, Region 1882 (S08E54,
Dao/beta-gamma-delta) produced an X2 flare that was associated with
Types II (2078 km/s) and IV radio emissions with another Castelli U
radio signature including a 370 sfu Tenflare. SOHO/LASCO C2 coronagraph
imagery depicted a partial-halo CME emerging from the east limb
beginning at 25/1512 UTC. WSA-Enlil model output suggest this CME will
merge with the ejecta from the 24 October M9 flare and arrive on the
28th.

Region 1882 also produced six M-class events, including an M1 flare at
26/0937 UTC. A Type II (1275 km/s) radio sweep was reported with this
flare, beginning at 26/0931 UTC and dimming was apparent in SDO/AIA 193
imagery south of the region. This event has yet to be observed in
available coronagraph imagery. Region 1882 continued to evolve in both
area, spot count and magnetic complexity.

Regions 1875 (N07W44, Ekc/beta-gamma-delta) and 1877 (S13W23,
Dhi/beta-gamma) remained the largest on the visible disk. Region 1875
grew slightly while 1877 was relatively stable. Between 26/0442-0747
UTC, EUV dimming was observed in SDO/AIA 193 imagery south of and
between Regions 1875 and 1877. A CME was subsequently observed in
SOHO/LASCO C2 imagery emerging from the west beginning at 26/0700 UTC.
This event has not yet been modeled, but a preliminary analysis using
available coronagraph imagery suggests it was moving at approximately
400 km/s and may have an Earth-directed component.

A second dimming event was observed between 26/0827-1015 UTC in the same
vicinity and brightening was evident in Regions 1875 and 1877 around the
same time as the M1 flare from Region 1882. This event has not yet been
observed in coronagraph imagery. Finally, a filament eruption was in
progress in the southwestern quadrant at the time of this writing.

25th October


Solar activity was high. Region 1882 (S08E67, Dso/beta) produced an
impulsive X1 flare (R3 Strong Radio Blackout), with no corresponding
optical report, at 25/0801 UTC. It was accompanied by Type II (1240
km/s) and IV radio emissions and a Tenflare (610 sfu). SOHO/LASCO C2
coronagraph imagery depicts a coronal mass ejection (CME) emerging from
the east limb beginning at 25/0824 UTC.

Earlier, this same region produced an M2 x-ray flare (R1 Minor Radio
Blackout) at 25/0302 UTC as well as Type II (711 km/s) and Type IV radio
emissions. A relatively narrow CME, believed to be associated with this
flare, was observed in SOHO/LASCO C2 coronagraph imagery emerging from
the east limb at 25/0424 UTC. Later, Region 1882 produced an M1/Sf
flare at 25/1012 UTC.

A 25 degree filament eruption in the northeast which occurred between
25/0004-0258 UTC produced a CME visible in SOHO/LASCO C2 imagery
beginning 25/0436 UTC. None of these CMEs are expected to be
geoeffective. Another filament liftoff from the southeast quadrant was
observed in SDO AIA 304 imagery 25/0600-1000 UTC.

Regions 1875 (N08W30, Ekc/beta-gamma-delta) and 1877 (S12W10, Dhi/beta)
remained the largest regions during the past 24 hours. Region 1875
ended Oct 24th with an area of 720 millionths and by the time of this
report had four C-class events to its credit. Region 1877 ended the 24th
at 440 millionths and was responsible for three C-class events so far,
including a C5 at 24/2210 UTC.

24th October


Solar activity was high. The largest flare of the period came from Region 1877 (S12E04, Dkc/beta-gamma-delta). An impulsive M9/1n (R2 – Moderate on the NOAA Scale) erupted at approximately 24/0030 UTC and was associated with Types II (est. speed 1321 km/s) and IV radio emissions. This region increased in area and maintained a delta in its intermediate spots. Region 1875 (N08W16, Ekc/beta-gamma-delta) continued to be the most active region, producing multiple C-class flares as well as several impulsive M-class (R1 – Minor on the NOAA Scale) flares during the period. These included an M2 at 23/2053 UTC, an M1 at 23/2343 UTC, an M3 at 24/0016 UTC, another M2 at 24/1009 UTC, and another M3 at 24/1033 UTC. This region maintained a beta-gamma-delta magnetic configuration, mainly in the intermediate spots. Yet another faint full-halo CME, associated with the M9/1n flare at 24/0030 UTC, was observed in Lasco C2 imagery at approximately 24/0148 UTC. Analysis is in progress to determine the possible impacts at Earth.

23rd October


Solar activity was moderate. Region 1875 (N09W05, Ekc/beta-gamma-delta)
continued to be the most active region, producing the vast majority of
the flare activity. It produced the two largest flares of the period, an
M1/Sf flare at 22/1520 UTC and an impulsive M4/1b at 22/2120 UTC. The M4
flare was associated with a 220 sfu Tenflare and a Type II radio sweep
(estimated shock speed 1955 km/s). This region continued to exhibit a
beta-gamma-delta magnetic configuration with separate deltas in its
trailer and intermediate spots. Region 1877 (S13E17,
Dki/beta-gamma-delta) decreased in area from 390 millionths to ~250
millionths, but developed a delta in its intermediate spots. It was also
responsible for a few low-level C-class flares throughout the period.

A faint, asymmetric full halo CME, associated with the M4/1b flare, was
observed in Lasco C2 imagery at ~22/2200 UTC. WSA Enlil analysis
indicates speeds of approximately 668 km/s with at least a portion of
the ejecta expected to impact the Earth early on 26 Oct. The current WSA
Enlil run has all four of the CMEs from the past three days included.

22nd October


Solar activity was low. Regions 1875 (N06E19, Ekc/beta-gamma-delta) and 1877 (S13E38, Cho/beta) were the most notable regions on the disk, and the most active. the largest event of the period was a C2/Sf, produced by Region 1875 at 21/2311 UTC. Additional analysis of the previously reported CMEs from 20 Oct suggests that two filament eruption-related events occurred during the past 36 hrs, both of which had potential for modest geoeffectiveness. Speed measurements of about 650 km/s and 430 km/s, respectively, were observed with the CMEs.