Viewing archive of Saturday, 24 September 2011
Solar activity report
Any mentioned solar flare in this report has a scaling factor applied by the Space Weather Prediction Center (SWPC). Because of the SWPC scaling factor, solar flares are reported as 42% smaller than for the science quality data. The scaling factor has been removed from our archived solar flare data to reflect the true physical units.
Report of Solar-Geophysical Activity 2011 Sep 24 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 267 Issued at 2200Z on 24 Sep 2011IA. Analysis of Solar Active Regions and Activity from 23-2100Z to 24-2100Z Solar activity was high. Region 1302 (N12E47) produced
a X1/2b flare at 24/0940Z, a M7 long duration x-ray flare at
24/1320Z, and a M5 x-ray flare at 24/2036Z. Coronal mass ejections
(CMEs) were observed in association with the first two of these
events. The second CME, which was must faster, appears to overtake
the first, and has a partial halo signature from the LASCO/Earth
perspective. Estimate speeds of the CME range between 1900 - 2600
km/s. Region 1302 produced three other flares greater than M1 during
the period. Region 1295 (N26W84) produced a M3 x-ray flare at
24/1725Z. Another large sunspot is beginning to emerge around the
East limb of the disk near N15.
IB. Solar Activity Forecast
Solar activity is expected to be high
to very high for the next 3 days (25-27 September) due to the
activity produced by Region 1302.
IIA. Geophysical Activity Summary 23-2100Z to 24-2100Z
The geomagnetic field was quiet. The greater than 10MeV proton flux
at geosynchronous orbit exceeded the 10 pfu threshold at 23/2255Z,
peaked at 12 pfu during the day, and remains above threshold at the
time of this report. The noon F10 solar flux was observed at 190,
but is believed to be enhanced by the flares which occurred today.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be mostly quiet to unsettled on day 1 (25 September) due
to recurrent coronal hole effects. Conditions are forecast to
increase to unsettled to minor storm levels with the chance for a
major storm starting late on day 1 through midday on day 2 (26
September) due to the anticipated partial impact from the CME from
earlier today. Conditions are forecast to carry over to day 3 (27
September) with mostly unsettled to active periods expected. The
greater than 10 MeV proton flux is expected to remain above the 10
pfu threshold for days 1 and 2, before decreasing on day 3.
III. Event Probabilities 25 Sep to 27 Sep
| Class M | 80% | 80% | 80% |
| Class X | 40% | 40% | 40% |
| Proton | 99% | 99% | 80% |
| PCAF | yellow | ||
IV. Penticton 10.7 cm Flux
Observed 24 Sep 190 Predicted 25 Sep-27 Sep 160/160/160 90 Day Mean 24 Sep 107
V. Geomagnetic A Indices
Observed Afr/Ap 23 Sep 002/003 Estimated Afr/Ap 24 Sep 005/005 Predicted Afr/Ap 25 Sep-27 Sep 010/010-025/030-012/012
VI. Geomagnetic Activity Probabilities 25 Sep to 27 Sep
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 40% | 10% | 10% |
| Minor storm | 30% | 50% | 40% |
| Major-severe storm | 01% | 30% | 20% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 40% | 10% | 10% |
| Minor storm | 30% | 60% | 60% |
| Major-severe storm | 01% | 30% | 30% |
All times in UTC
Latest news
Sunday, 1 February 2026
Complex sunspot region 4366
Monday, 19 January 2026
CME impact! S4 solar radiation storm
Sunday, 18 January 2026
X1.9 solar flare with earth-directed CME
Latest forum messages
Current Farside Activity 357X8 CME 89Space Weather Memes 789Incoming & Unnumbered Active Regions 151AR4362 17
More topicsSupport SpaceWeatherLive.com!
A lot of people come to SpaceWeatherLive to follow the Solar activity or if there is a chance to see the aurora, but with more traffic comes higher costs to keep the servers online. If you like SpaceWeatherLive and want to support the project you can choose a subscription for an ad-free site or consider a donation. With your help we can keep SpaceWeatherLive online!
Space weather facts
| Last X-flare | 2026/02/04 | X4.3 |
| Last M-flare | 2026/02/05 | M1.1 |
| Last geomagnetic storm | 2026/02/05 | Kp5+ (G1) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| December 2025 | 124 +32.2 |
| February 2026 | 140.8 +16.8 |
| Last 30 days | 124.4 +17 |