Last major update issued on October 18, 2007 at 04:50 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update October 4, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update October 3, 2007)]
The geomagnetic field was very quiet on October 17. Solar wind speed ranged between 288 and 333 km/s (average speed was 310 km/s, increasing 7 km/s over the previous day). The first part of the stream from CH295 arrived near midnight.
Solar flux measured at 20h UTC on 2.8 GHz was 67.4. The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 0.8). Three hour interval K indices: 10000001 (planetary), 10000110 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day.
October 15-17: No obvious fully or partly Earth directed CMEs were observed in LASCO imagery.
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 trans equatorial hole (CH295) was in an Earth facing position on October 15-18. CH295 has become less well defined over the last solar rotation and has significantly decreased its areal coverage. A recurrent coronal hole (CH296) will rotate into an Earth facing position on October 21-22. CH296 has become less well defined in the northern part and may cause a less significant disturbance this time.
Processed SOHO/EIT 195 image at 02:13 UTC on October 18. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor to fair.
Monitoring remarks from a location near N58E06: October 16-17: Puerto Rico was noted on 1480 and 1520 kHz as early as 21:40 UTC. Signals from the east coast of North America were not as abundant as they've been recently and certainly weaker. The best Trans Atlantic propagation sector was 255-280 degrees.
The geomagnetic field is expected to be quiet to unsettled on October 18-19, possible with an isolated active interval. Quiet to active conditions are likely on October 20-21 due to a high speed stream from CH295. Quiet is expected for October 22-23, while October 24-25 could see quiet to minor storm conditions due to effects from CH296.
|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.
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:||0||0|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2007.04||72.4||3.7||(10.1 predicted, -0.7)|
|2007.05||74.4||11.7||(9.0 predicted, -1.1)|
|2007.06||73.7||12.0||(8.0 predicted, -1.0)|
|2007.07||71.6||10.0||(7.3 predicted, -0.7)|
|2007.08||69.1||6.2||(6.8 predicted, -0.5)|
|2007.09||67.1||2.4||(6.9 predicted, +0.1)|
|2007.10||67.8 (1)||1.3 (2)||(7.6 predicted, +0.7)|
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.