Viewing archive of Friday, 28 September 2007

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 2007 Sep 28 2203 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 271 Issued at 2200Z on 28 Sep 2007

IA. Analysis of Solar Active Regions and Activity from 27-2100Z to 28-2100Z

Solar activity was very low. No flares occurred during the past 24 hours. Newly numbered Region 971 (N03E07) emerged on disk and is a small, C-type sunspot group.
IB. Solar Activity Forecast
Solar activity is expected to be very low.
IIA. Geophysical Activity Summary 27-2100Z to 28-2100Z
The geomagnetic field was unsettled to active from 27/2100Z through 28/1200Z. Conditions were quiet from 1200-1800Z but returned to unsettled to active from 1800-2100Z. Real-time solar wind measurements from ACE showed a steady increase in solar wind speed from about 27/1700Z through about 28/0900Z. After 0900Z solar wind speed began to decline, but a second increase in speed and total field began around 1500Z and has continued through forecast issue time 28/2100Z. Both increases show signatures consistent with a coronal hole high speed stream.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be mostly active with a chance for minor storm periods at high latitudes for the first day (29 September) due to the continuation of the high speed stream. Activity is expected to decrease to mostly unsettled levels for the second day (30 September) and should be quiet to unsettled on the third day (01 October).
III. Event Probabilities 29 Sep to 01 Oct
Class M01%01%01%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       28 Sep 067
  Predicted   29 Sep-01 Oct  067/067/067
  90 Day Mean        28 Sep 069
V. Geomagnetic A Indices
  Observed Afr/Ap 27 Sep  010/019
  Estimated     Afr/Ap 28 Sep  015/018
  Predicted    Afr/Ap 29 Sep-01 Oct  020/025-010/012-007/008
VI. Geomagnetic Activity Probabilities 29 Sep to 01 Oct
A. Middle Latitudes
Minor storm20%15%05%
Major-severe storm10%05%01%
B. High Latitudes
Minor storm25%15%10%
Major-severe storm15%10%01%

All times in UTC

<< Go to daily overview page

Latest news


A lot of people come to SpaceWeatherLive to follow the Sun's activity or if there is aurora to be seen, but with more traffic comes higher server costs. Consider a donation if you enjoy SpaceWeatherLive so we can keep the website online!

Support SpaceWeatherLive with our merchandise
Check out our merchandise

Latest alerts

Get instant alerts!

Space weather facts

Last X-flare2024/05/15X2.9
Last M-flare2024/05/23M1.7
Last geomagnetic storm2024/05/17Kp6 (G2)
Spotless days
Last spotless day2022/06/08
Monthly mean Sunspot Number
April 2024136.5 +31.6
May 2024153.8 +17.3
Last 30 days152.9 +22.5

This day in history*

Solar flares
*since 1994

Social networks