Last major update issued on May 30, 2006 at 03:35 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
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electron fluence charts (updated daily)]
[Solar cycles 21-23
(last update April 1, 2006)]
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[Graphical comparison
of cycles 21, 22 and 23 (last update April 1, 2006)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 1, 2006)]
[Historical solar and
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[Archived reports (last update
May 3, 2006)]
The geomagnetic field was inactive to very quiet on May 29. Solar wind speed ranged between 284 and 311 (all day average 296) km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 81.1. The planetary A index
was 3 (STAR Ap - based on the mean of three hour interval ap
indices: 2.8).
Three hour interval K indices: 11000101 (planetary), 10001111 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10886 decayed slowly and quietly.
Region 10887 was mostly unchanged and quiet.
Region 10889 decayed and had two tiny spots left at midnight. The region
will likely become spotless today.
Region 10890 decayed quickly and could become spotless today.
Spotted regions not numbered by NOAA/SEC:
[S658] This region emerged to the east of region 10887 on May 29.
Location at midnight: S13E32
May 27-29: No partly or fully Earth directed CMEs were observed in limited LASCO imagery.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago
A recurrent trans equatorial coronal hole (CH226) was in an Earth facing position on May 29-30.
Processed SOHO/EIT 284 image at 19:06 UTC on May 26. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet on May 30 and quiet to unsettled on May 31. Quiet to active conditions are likely on June 1-3 due to a high speed stream from CH226.
| 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. Propagation on long distance northeast-southwest paths is fair to good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay had the best signal tonight, however, there was some competition from at least one station from Argentina. Radio América (Paraguay) on 1480 kHz was excellent just after LSR and at the same time 920 Radio Nacional was audible. 1590 Radio Real had a good signal from 1 hour before LSR until 20 minutes past. Otherwise most of the stations heard were from Argentina.
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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10885 | 2006.05.20 | S12W80 | plage | ||||
| 10886 | 2006.05.23 | 1 | 2 | N08W40 | 0020 | HSX | |
| 10887 | 2006.05.26 | 6 | 2 | S12E24 | 0030 | CAO | classification was HAX at midnight, location S12E22 |
| 10889 | 2006.05.27 | 2 | 2 | S01W20 | 0010 | HSX | classification was AXX at midnight, area 0000 |
| 10890 | 2006.05.28 | 5 | 3 | S13W42 | 0030 | CSO | classification was CAO at midnight, area 0010 |
| S658 | 2006.05.29 | 3 | S13E32 | 0010 | CAO | ||
| Total spot count: | 14 | 12 | |||||
| SSN: | 54 | 62 | |||||
| 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) |
| 2005.02 | 97.2 | 29.2 | 33.9 (-0.7) |
| 2005.03 | 89.9 | 24.5 | 33.5 (-0.4) |
| 2005.04 | 86.0 | 24.2 | 31.6 (-1.9) |
| 2005.05 | 99.3 | 42.7 | 28.9 (-2.7) |
| 2005.06 | 93.7 | 39.3 | 28.8 (-0.1) |
| 2005.07 | 96.4 | 40.1 | 29.1 (+0.3) |
| 2005.08 | 90.5 | 36.4 | 27.4 (-1.7) |
| 2005.09 | 91.1 | 21.9 | 25.8 (-1.6) |
| 2005.10 | 77.0 | 8.5 | 25.5 (-0.3) |
| 2005.11 | 86.3 | 18.0 | (24.5 predicted, -1.0) |
| 2005.12 | 90.7 | 41.2 | (21.8 predicted, -2.7) |
| 2006.01 | 83.4 | 15.4 | (18.7 predicted, -3.1) |
| 2006.02 | 76.5 | 4.7 | (15.6 predicted, -3.1) |
| 2006.03 | 75.4 | 10.8 | (13.4 predicted, -2.2) |
| 2006.04 | 89.0 | 30.2 | (12.7 predicted, -0.7) |
| 2006.05 | 81.0 (1) | 36.5 (2) | (12.2 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.
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