Last major update issued on May 27, 2010 at 01:30 UTC.
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The geomagnetic field was quiet on May 26. Solar wind speed ranged between 275 and 352 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 72.4. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.8). Three hour interval K indices: 22111122 (planetary), 22222212 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight there were 2 spotted regions on the visible solar disk.
Region 11072 was quiet and stable.
Spotted regions not numbered by NOAA/SWPC:
[S769] This region emerged in the northern hemisphere near the central meridian on May 26. Location at midnight: N15W03
May 25-26: No obvious Earth directed CMEs were observed in LASCO or
May 24: A partial halo CME was observed in LASCO images and was associated with another filament eruption in the same location as one day earlier.
May 23: A full halo CME was observed in LASCO images after a filament eruption in the northwest quadrant, this was associated with a long duration B1.3 event peaking at 18:01 UTC.
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 well defined recurrent coronal hole (CH406) in the northern hemisphere will likely rotate into an Earth facing position on May 27-28.
Processed SOHO/EIT 195 image at 00:00 UTC on May 27. 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 to active with a chance of minor storm intervals on May 27-28 due to CME effects. Quiet to unsettled conditions are likely on May 29-30 while a high speed stream from CH406 could cause unsettled to major storm on May 31.
|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||SWPC
|Total spot count:||1||2|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
cycle 23 sunspot max.
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2009.07||68.2||3.5||3.6 (+0.9)||5.49 / 4.55|
|2009.08||67.3||0.0||4.8 (+1.2)||5.70 / 4.89|
|2009.09||70.5||4.2||6.1 (+1.3)||3.88 / 3.61|
|2009.10||72.6||4.6||7.0 (+0.9)||3.66 / 3.56|
|2009.11||73.6||4.2||(7.7 predicted, +0.7)||2.45 / 2.63|
|2009.12||76.7||10.6||(8.9 predicted, +1.2)||1.41 / 1.92|
|2010.01||81.1||13.1||(10.2 predicted, +1.3)||2.93 / 3.07|
|2010.02||84.7||18.6||(11.8 predicted, +1.6)||4.15 / 4.61|
|2010.03||83.4||15.4||(13.7 predicted, +1.9)||4.58 / 4.65|
|2010.04||75.9||7.9||(15.3 predicted, +1.8)||10.22 / 10.24|
|2010.05||73.9 (1)||15.4 (2)||(16.6 predicted, +1.3)||(7.82)|
1) Running average based on the
daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Current impact on the monthly SSN based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official international sunspot number is typically 30-50% lower.
3) Running average based on the daily SWPC ap indices. Values in red are based on the official NGDC ap indices.
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.