Last major update issued on September 28, 2006 at 03:10 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 3, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 3, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 3, 2006)]
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[Archived reports (last update September 8, 2006)]
The geomagnetic field was quiet to unsettled on September 27. Solar wind speed ranged between 364 and 472 km/s (all day average 428 km/s - decreasing 69 km/s from the previous day).
Solar flux measured at 20h UTC on 2.8 GHz was 72.0. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.9). Three hour interval K indices: 32011001 (planetary), 32021110 (Boulder).
The background x-ray flux is at 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.
Spotted regions not numbered by NOAA/SEC:
[S676] This region rotated into view at the southeast limb on September 27. Location at midnight: S18E80.
September 25-27: No obvious partly or fully Earth directed CMEs were detected in incomplete 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 recurrent coronal hole (CH241) in the southern hemisphere was in an Earth facing position on September 25-27. A small, poorly defined coronal hole in the northern hemisphere was in a potentially geoeffective position on September 27
Processed SOHO/EIT 284 image at 19:06 UTC on September 27. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet most of September 28. Quiet to active conditions are likely from late on September 28 until September 30 due to a high speed stream from CH241. Occasional minor storm intervals are possible. Quiet to unsettled conditions are likely on October 1-3.
|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 very poor.
Only the most common east coast North American stations were heard during the night, none with impressive signals. The best propagation was noted to Venezuela and Colombia (fair signals noted on 760, 980, 1230 and 1250 kHz). By 03h UTC propagation was still poor towards the North American east coast. Interestingly 1000 KOMO and 1510 KGA both became audible at this time with KOMO reaching a fair signal level.
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|
|Total spot count:||1||1|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2006.03||75.4||10.8||(17.1 predicted, -1.5)|
|2006.04||89.0||30.2||(16.4 predicted, -0.7)|
|2006.05||80.9||22.2||(15.9 predicted, -0.5)|
|2006.06||76.5||13.9||(14.1 predicted, -1.8)|
|2006.07||75.7||12.2||(12.4 predicted, -1.7)|
|2006.08||79.0||12.9||(11.9 predicted, -0.5)|
|2006.09||78.0 (1)||20.7 (2)||(11.9 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.