Last major update issued on August 27, 2009 at 04:25 UTC.
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The geomagnetic field was quiet to unsettled on August 26. Solar wind speed ranged between 312 and 357 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 67.3. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.1). Three hour interval K indices: 31210001 (planetary), 31220000 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight the visible solar disk was spotless (consecutive spotless days: 47).
August 24-26: No partially or fully Earth directed CMEs were observed in LASCO and STEREO 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
No obvious coronal holes are currently in or near Earth facing positions.
Processed SOHO/EIT 195 image at 23:36 UTC on August 26. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be mostly quiet on August 27-31.
| 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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
| Active region | Date numbered | SWPC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| Total spot count: | 0 | 0 | |||||
| SSN: | 0 | 0 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2008.05 | 68.4 | 3.2 | 3.5 (+0.2) |
| 2008.06 | 65.8 | 3.4 | 3.2 (-0.3) |
| 2008.07 | 65.7 | 0.5 | 2.8 (-0.4) |
| 2008.08 | 66.5 | 0.5 | 2.6 (-0.2) |
| 2008.09 | 67.1 | 1.1 | 2.3 (-0.3) |
| 2008.10 | 68.3 | 2.9 | 1.83 (-0.5) |
| 2008.11 | 68.6 | 4.1 | 1.75 (-0.08) |
| 2008.12 | 69.2 | 0.8 | 1.7 (-0.05) probably the sunspot minimum |
| 2009.01 | 69.8 | 1.5 | 1.8 (+0.1) |
| 2009.02 | 70.0 | 1.4 | (2.1 predicted, +0.3) |
| 2009.03 | 69.2 | 0.7 | (2.4 predicted, +0.3) |
| 2009.04 | 69.7 | 1.2 | (2.8 predicted, +0.4) |
| 2009.05 | 70.5 | 2.9 | (3.3 predicted, +0.5) |
| 2009.06 | 68.6 | 2.6 | (4.0 predicted, +0.7) |
| 2009.07 | 68.2 | 3.5 | (5.2 predicted, +1.2) |
| 2009.08 | 67.2 (1) | 0.0 (2) | (6.1 predicted, +0.9) |
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/SWPC) 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.