Last major update issued on September 27, 2004 at 02:45 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update August 28, 2004)]
[Archived reports (last update September 27, 2004)]
The geomagnetic field was quiet on September 26. Solar wind speed ranged between 331 and 364 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 89.5. The planetary A
index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 5.4).
Three hour interval K indices: 11211222 (planetary), 11212111 (Boulder).
The background x-ray flux is at the class A5 level.
At midnight there were 2 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10673 was quiet and stable. The region will rotate out of view at the southwest limb today.
Region 10675 was quiet and stable.
September 24-26: No obviously earth directed CMEs observed in limited LASCO data set.
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
No obvious coronal holes are currently approaching geoeffective positions. There is a large, mostly poorly defined coronal hole in the northern hemisphere, however, its southward extension does not appear to reach far enough south to become geoeffective.
Processed SOHO/EIT 284 image at 19:06 UTC on September 10. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be mostly quiet on September 27-29. A recurrent coronal hole flow could arrive on September 27, however, currently available images do not indicate the presence of a geoeffective coronal hole.
|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 fair to occasionally good. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and WLAM Lewiston ME. On other frequencies many signals from the easternmost part of North America were noted, stations from Puerto Rico and the Dominican Republic could be heard as well.
Local sunrise propagation on September 26 was somewhat unusual with Newfoundland stations coming in well, virtually no northeast US stations noted and Florida stations noted on 610, 790 and 940 kHz. Propagation was best towards Cuba.
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:||2||2|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.03||112.0||49.1||(47.0 predicted, -2.3)|
|2004.04||101.2||39.3||(44.8 predicted, -2.2)|
|2004.05||99.8||41.5||(41.5 predicted, -3.3)|
|2004.06||97.4||43.2||(38.6 predicted, -2.9)|
|2004.07||119.1||51.0||(36.8 predicted, -1.8)|
|2004.08||109.6||40.9||(35.4 predicted, -1.4)|
|2004.09||105.2 (1)||46.6 (2)||(34.2 predicted, -1.2)|
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% less.
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.