Viewing archive of Friday, 28 December 2001

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 2001 Dec 28 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 362 Issued at 2200Z on 28 Dec 2001

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

Solar activity was high. An X3.4 flare from an apparent east limb source occurred at 28/2045 UTC, and remained in progress at the end of the period. This event was accompanied by bright loops visible in h-alpha imagery behind the east limb near S27. A fainter prominence was also visible on the northwest limb near the approximate location of Region 9742 (N12W94), but the lack of subsequent energetic particle enhancements seems to favor the east limb source. Other activity included an impulsive M4/Sf from Region 9742 at 28/0351 UTC, and weaker M-class events from Regions 9748 (S11W76) and 9754 (S08W02). Two new regions were numbered today: 9764 (N12E15) and 9765 (N05E77).
IB. Solar Activity Forecast
Solar activity is expected to remain moderate to high for the next three days.
IIA. Geophysical Activity Summary 27-2100Z to 28-2100Z
The geomagnetic field was quiet to unsettled. The greater than 10 MeV proton event which had been in progress since 26 December ended today. The event began at 26/0605 UTC, reached a maximum flux of 779 pfu at 26/1115 UTC, and ended at 28/1040 UTC.
IIB. Geophysical Activity Forecast
The increase in geomagnetic field activity, which had been expected for today, has not yet occurred, but precursors in solar wind data from the ACE satellite suggest that a shock arrival may still yet occur, perhaps within the next 10 hours or so. Uncertainty in the earthward speed of shock propagation from the CME event of 26 December is a likely cause for the delay, though this event could also miss the Earth. Unsettled to minor storm conditions, and isolated major storms conditions at higher latitudes, remain possible within the first day of the forecast period. Predominantly quiet to unsettled conditions are expected thereafter.
III. Event Probabilities 29 Dec to 31 Dec
Class M75%75%75%
Class X10%10%10%
IV. Penticton 10.7 cm Flux
  Observed       28 Dec 263
  Predicted   29 Dec-31 Dec  260/255/255
  90 Day Mean        28 Dec 218
V. Geomagnetic A Indices
  Observed Afr/Ap 27 Dec  010/006
  Estimated     Afr/Ap 28 Dec  012/010
  Predicted    Afr/Ap 29 Dec-31 Dec  025/030-012/015-008/010
VI. Geomagnetic Activity Probabilities 29 Dec to 31 Dec
A. Middle Latitudes
Minor storm20%05%05%
Major-severe storm05%01%01%
B. High Latitudes
Minor storm25%10%05%
Major-severe storm10%05%01%

All times in UTC

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