Last major update issued on May 27, 2006 at 05:10 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
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(last update April 1, 2006)]
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[Graphical
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[Historical solar and
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[Archived reports (last update
May 3, 2006)]
The geomagnetic field was inactive to slightly unsettled on May 26. Solar wind speed ranged between 303 and 336 (all day average 324) km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 81.6. The planetary A index
was 5 (STAR Ap - based on the mean of three hour interval ap
indices: 4.8).
Three hour interval K indices: 31001112 (planetary), 21001001 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight there were 4 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 10885 decayed further and could become spotless today.
Region 10886 lost the trailing spots while the leader spot was mostly
unchanged.
New region 10887 rotated into view at the southeast limb on May 25 and
was numbered the next day by NOAA/SEC.
New region 10888 emerged in the northwest quadrant.
May 24 and 26: No partly or fully Earth directed CMEs were observed in LASCO
imagery.
May 25/26: A very faint halo CME was observed in LASCO images early on
May 26. Its source was likely a B class event in region 10885 late on May 25.
This CME could reach Earth on May 29.
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) will likely rotate into 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 mostly quiet on May 27-28 and quiet to active on May 29 or 30 due to weak CME effects.
| 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 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 a fair to occasionally good signal tonight. Other stations from Uruguay like 930 Montecarlo and 1590 Real had fair to good peaks. At and just after LSR quite a few stations from Argentina popped up with fair to good signals (700, 710, 950, 1030, 1190 kHz), as did Paraguay on 1020.06 and 1480 kHz.
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 |
|---|---|---|---|---|---|---|---|
| 10884 | 2006.05.19 | S12W44 | plage | ||||
| 10885 | 2006.05.20 | 3 | 3 | S12W38 | 0040 | CRO | area was 0020 at midnight |
| 10886 | 2006.05.23 | 3 | 1 | N08E04 | 0060 | CSO | classification was HSX at midnight |
| 10887 | 2006.05.26 | 2 | 3 | S12E64 | 0030 | BXO | formerly region S656 classification was DRO at midnight |
| 10888 | 2006.05.26 | 3 | 5 | N05W64 | 0070 | CSO | area was 0030 at midnight |
| Total spot count: | 11 | 12 | |||||
| SSN: | 51 | 52 | |||||
| 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 | 80.8 (1) | 30.0 (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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