Last major update issued on August 28, 2007 at 05:30 UTC.
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The geomagnetic field was quiet to active on August 27. Solar wind speed ranged between 480 and 696 km/s (average speed was 605 km/s, increasing 202 km/s over the previous day) under the influence of a high speed stream from CH287.
Solar flux measured at 20h UTC on 2.8 GHz was 69.2. The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.3). Three hour interval K indices: 32422233 (planetary), 33422222 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10969 was quiet and stable.
August 25-27: No obvious fully or partly Earth directed CMEs were observed in LASCO imagery.
history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A recurrent coronal hole (CH288) in the southern hemisphere could rotate into an Earth facing position on August 28, the coronal hole could be too far to the south to cause a disturbance.
Processed STEREO 195 image at 19:15 UTC on August 27. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair.
Monitoring remarks from a location near N58E06: August 27-28: Several stations from Brazil were heard unexpectedly early in the evening. Already at 21h UTC I had audio from 2 stations on 1320 kHz. Propagation became somewhat poorer over the next couple of hours and only 1470 Radio Cristal (Uruguay) was heard of TA stations outside of Brazil. No monitoring at LSR.
The geomagnetic field is expected to be quiet to unsettled on August 28 due to effects from CH287. Quiet conditions are likely on August 29-31. There is a chance of a few unsettled intervals on September 1 due to effects from CH288.
|Coronal holes (1)||Coronal mass ejections (2)||M and X class flares (3)|
1) Effects from a coronal hole could reach Earth
within the next 5 days. When the high speed stream has arrived the
color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
|Active region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
|10969||2007.08.21||2||1||S05W05||0100||HAX||classification was HSX at midnight|
|Total spot count:||2||1|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2007.02||77.7||10.6||(11.6 predicted, -0.4)|
|2007.03||72.2||4.8||(11.1 predicted, -0.5)|
|2007.04||72.4||3.7||(10.8 predicted, -0.3)|
|2007.05||74.4||11.7||(10.4 predicted, -0.4)|
|2007.06||73.7||12.0||(10.3 predicted, -0.1)|
|2007.07||71.6||10.0||(10.5 predicted, +0.2)|
|2007.08||68.9 (1)||8.1 (2)||(11.0 predicted, +0.5)|
1) Running average based on the
daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% lower.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.