Viewing archive of Sunday, 19 September 2004

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 2004 Sep 19 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 263 Issued at 2200Z on 19 Sep 2004

IA. Analysis of Solar Active Regions and Activity from 18-2100Z to 19-2100Z

Solar activity was moderate. Region 672 (N05W58), which has been in a decay phase over the last 72 hours, produced two notable events this period. The first was an extended C3.8 flare at 19/1148Z that erupted along a filament channel just north of the spot cluster. The second was an M1.9 flare at 19/1712Z. This impressive flare had associated Type II (604 km/s) and Type IV radio sweeps; a 520 sfu Tenflare, and a greater than 10 MeV proton event. LASCO imagery was unavailable. Region 672 is a C-type beta spot group with under 100 millionths of white light area coverage. Region 673 (S13E22) showed little change this period and continues to produce occasional B-class flare activity.
IB. Solar Activity Forecast
Solar activity is expected to be low to very low. There is a small chance of another M-class flare from Region 672 before it rotates around the west limb early on 22 September. Occasional C-class flares are possible from Region 673.
IIA. Geophysical Activity Summary 18-2100Z to 19-2100Z
The geomagnetic field was quiet. Solar wind speed was generally below 400 km/s. A greater than 10 MeV proton event followed today's M1 flare at 19/1712Z. The proton event began at 19/1925Z and was still in progress at the time of issue. The maximum flux value so far was 35 pfu at 19/2025Z. A greater than 100 MeV proton flux enhancement was also observed, but has not exceeded the 1 pfu event threshold. The greater than 2 MeV electron flux at geosynchronous orbit was at high levels.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to remain at mostly quiet to unsettled levels on 20 and 21 September. A disturbance associated with today's M1 flare and CME is expected to occur on 22 September: Active to minor storm periods are likely. The greater than 10 MeV proton event in progress now is expected to end by 21 September.
III. Event Probabilities 20 Sep to 22 Sep
Class M15%10%10%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       19 Sep 105
  Predicted   20 Sep-22 Sep  100/095/090
  90 Day Mean        19 Sep 112
V. Geomagnetic A Indices
  Observed Afr/Ap 18 Sep  016/016
  Estimated     Afr/Ap 19 Sep  005/008
  Predicted    Afr/Ap 20 Sep-22 Sep  005/008-008/012-015/020
VI. Geomagnetic Activity Probabilities 20 Sep to 22 Sep
A. Middle Latitudes
Minor storm01%05%10%
Major-severe storm01%01%05%
B. High Latitudes
Minor storm05%10%20%
Major-severe storm01%01%10%

All times in UTC

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