Last major update issued on May 31, 2009 at 05:05 UTC. Minor update posted at 15:55 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 April 12, 2009)]
The geomagnetic field was quiet on May 30. Solar wind speed ranged between 342 and 351 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 68.5. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 22000001 (planetary), 22100111 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight the visible solar disk was spotless.
Update posted at 15:55 UTC on May 31: Two spotted regions are currently visible in the northern hemisphere. One is at N26E46 (developing moderately quickly), the other one at N21E01 (slow development).
May 28-30: No partially or fully Earth directed CMEs were observed in 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 small, poorly defined, recurrent coronal hole (CH370) in the northern hemisphere was in an Earth facing position on May 29-30.
Processed SOHO/EIT 195 image at 00:24 UTC on May 31. 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 fair. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet on May 31 becoming quiet to unsettled on June 1-2 due to weak effects from CH370.
|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|
|Total spot count:||0||0|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
sunspot minimum candidate month
|2008.11||68.6||4.1||(1.8 predicted, -0.1)
sunspot minimum candidate month
|2008.12||69.2||0.8||(1.9 predicted, +0.1)|
|2009.01||69.8||1.5||(2.2 predicted, +0.3)|
|2009.02||70.0||1.4||(2.6 predicted, +0.4)|
|2009.03||69.2||0.7||(3.0 predicted, +0.4)|
|2009.04||69.7||1.2||(3.4 predicted, +0.4)|
|2009.05||70.5 (1)||3.5 (2)||(4.0 predicted, +0.6)|
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/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.