Last major update issued on September 27, 2005 at 04:10 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 3, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 3, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 3, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update September 14, 2005)]
The geomagnetic field was quiet to active on September 26. Solar wind speed ranged between 347 and 407 (all day average 370) km/sec. The atypical disturbance displaying unusual changes in solar wind speed, density and temperature continued all day.
Solar flux measured at 20h UTC on 2.8 GHz was 81.3. The planetary
index was 14 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 43234223 (planetary), 43234323 (Boulder).
The background x-ray flux is at the class A4 level.
At midnight there were 2 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 10810 decayed slowly and quietly.
Region 10812 was quiet and stable.
A bipolar area with the expected polarity alignment of cycle 24 emerged in the southern hemisphere during the day and was located at S34E02 at midnight. As far as I could tell no spots were observable.
September 24-26: No obvious fully or partly Earth directed CMEs were observed.
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 coronal hole (CH188) in the southern hemisphere may have been in an Earth facing position on September 24, however, there is a chance CH188 may have been too far to the south to become geoeffective. Anyway CH188 has lost a significant portion of its area over the last rotation. A recurrent trans equatorial coronal hole (CH189) will rotate to an Earth facing position on September 26-27. The brief appearance on September 26 of a spotted region in the western part of CH189 caused a reduction in the size of the coronal hole.
Processed SOHO/EIT 284 image at 01:06 UTC on September 27. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on September 27-28 and become unsettled to active on September 29-30 due to a high speed stream from CH189.
|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) Material from a CME is likely to impact 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. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay with an occasionally strong signal, after 0330 UTC Radio Vibración (Venezuela) became dominant.
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|
|10810||2005.09.17||3||1||N08W49||0140||CHO||classification was HAX at midnight|
|Total spot count:||5||4|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2005.03||89.9||24.5||(33.5 predicted, -0.4)|
|2005.04||86.0||24.4||(32.2 predicted, -1.3)|
|2005.05||99.3||42.6||(29.9 predicted, -2.3)|
|2005.06||93.7||39.6||(28.7 predicted, -1.2)|
|2005.07||96.4||39.9||(27.7 predicted, -1.0)|
|2005.08||90.5||36.4||(25.8 predicted, -1.9)|
|2005.09||93.7 (1)||36.5 (2)||(24.2 predicted, -1.6)|
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.