Last major update issued on October 21, 2009 at 04:15 UTC.
[Solar and 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 September 13, 2009)]
The geomagnetic field was very quiet on October 20. Solar wind speed ranged between 282 and 308 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 71.0. The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 0.9). Three hour interval K indices: 10000000 (planetary), 00001100 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight the visible solar disk was spotless.
October 19-20: No partially or fully Earth directed CMEs were observed in LASCO
or STEREO imagery.
October 17-18: A partial halo CME associated with a filament eruption in the southern hemisphere was observed late on Oct.17 and early on Oct.18.
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
No obvious coronal holes are currently in potentially geoeffective positions.
Processed SOHO/EIT 195 image at 00:00 UTC on October 21. 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 good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on October 21-26. There's a chance of unsettled intervals on October 21 due to effects from CH383 and possible 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.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
|Active region||Date numbered||SWPC
|Location at midnight||Area||Classification||Comment|
|11028||2009.10.20||1||N26E51||0010||AXX||spotless at midnight|
|Total spot count:||1||0|
flux at Earth
|International sunspot number (SIDC)||Smoothed sunspot number|
cycle 23 sunspot max.
probably the sunspot minimum
|2009.04||69.7||1.2||(2.3 predicted, +0.3)|
|2009.05||70.5||2.9||(2.6 predicted, +0.3)|
|2009.06||68.6||2.6||(3.1 predicted, +0.5)|
|2009.07||68.2||3.5||(3.9 predicted, +0.8)|
|2009.08||67.3||0.0||(4.8 predicted, +0.9)|
|2009.09||70.5||4.2||(5.9 predicted, +1.1)|
|2009.10||70.3 (1)||0.7 (2)||(6.8 predicted, +0.9)|
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/SWPC) 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.