Last major update issued on August 21, 2006 at 03:55 UTC.
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The geomagnetic field was quiet to major storm on August 20. Solar wind speed ranged between 345 and 505 km/s (all day average 414 km/s - decreasing 12 km/s from the previous day).
Solar flux measured at 20h UTC on 2.8 GHz was 88.5. The planetary A index
was 24 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 56202432 (planetary), 56213422 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 3 C class events was recorded during the day.
Region 10904 decayed slowly and lost all spots outside of the leading penumbra. Flares: C1.5 long duration event peaking at 13:44, C2.9 at 16:32 and C4.3 at 21:09 UTC.
Spotted regions not numbered by NOAA/SEC:
[S672] This region rotated partly into view at the southeast limb late on August 20. Early on August 21 this regions produced 2 flares, C3.6 ar 00:50 and C3.8 at 02:26 UTC. Based on the current activity there is a fair chance of a minor M class flare from this region. Location at midnight: S07E85.
August 18-20: No partly or fully Earth directed CMEs were detected in LASCO imagery.
Coronal hole 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 small coronal hole in the southern hemisphere was probably located just too far to the south to be geoeffective, it rotated across the central meridian on August 18.
Processed SOHO/EIT 284 image at 19:08 UTC on August 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to major storm on August 20 and quiet to unsettled on August 21-22.
|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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. 1510 WWZN was noted with a weak to fair signal. Propagation on long distance northeast-southwest paths is fair with a mix of stations from Brazil, Argentina and Uruguay.
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|
|10904||2006.08.09||5||2||S14W72||0520||CKO||classification was HKX at midnight, area 0380|
|S672||2006.08.20||1||S07E85||0100||HSX||region only partly visible|
|Total spot count:||5||3|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2006.02||76.5||4.7||(18.4 predicted, -2.4)|
|2006.03||75.4||10.8||(16.6 predicted, -1.8)|
|2006.04||89.0||30.2||(15.9 predicted, -0.7)|
|2006.05||80.9||22.2||(15.1 predicted, -0.8)|
|2006.06||76.5||13.9||(12.9 predicted, -2.2)|
|2006.07||75.7||12.2||(11.4 predicted, -1.5)|
|2006.08||79.6 (1)||13.5 (2)||(11.4 predicted, -0.0)|
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.