Last major update issued on May 30, 2011 at 04:50 UTC.
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The geomagnetic field was unsettled to major storm on May 29. Solar wind speed ranged between 610 and 963 km/s under the influence of a high speed stream from CH451.
Solar flux measured at 20h UTC on 2.8 GHz was 110.8 (increasing 1.0 over the last solar rotation). The planetary A index was 32 (STAR Ap - based on the mean of three hour interval ap indices: 32.3). Three hour interval K indices: 46543543 (planetary), 35543543 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight UTC the visible solar disk had 9 spotted regions.
Region 11222 developed further and could produce C flares.
Region 11223 was quiet and stable.
Region 11224 decayed losing penumbral area and spots. Flare: C5.9 at 01:59 UTC.
Region 11225 was quiet and stable.
Region 11226 decayed in the trailing spot section after the M flare. There's significant polarity intermixing and the region currently has two minor magnetic delta structures. Another M class flare is possible. Flares: C1.0 at 05:31, C2.6 at 07:30, C3.7 at 09:24, C3.0 at 09:47, M1.4/1F long duration event peaking at 10:33 (associated with a large CME off the east limb) and C7.7 at 11:39 UTC.
New region 11227 rotated into view at the southeast limb on May 28 and was numbered the next day by NOAA/SWPC. The region developed significantly in the leading spot section with a magnetic delta structure forming. This delta disappeared after the C8 event. Flare: C8.7 at 21:22 UTC. This event was associated with a fast CME where the main part of the ejected material was observed off the southeast limb. However, LASCO images indicate the possibility of a full halo CME (very weak over the western limbs).
New region 11228 rotated into view at the northeast limb on May 28 and was numbered the next day by NOAA/SWPC.
Spotted regions not numbered by NOAA/SWPC:
[S1039] emerged in the northeast quadrant on May 29. Location at midnight: N15E53.
[S1040] emerged in the northwest quadrant on May 29. Location at midnight: N12W25.
May 27-28: No obviously Earth directed CMEs were observed in LASCO
and STEREO imagery.
May 29: The CME observed after the C8 event in region 11227 may have Earth directed parts (pending further analysis).
Coronal hole history (since late October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
The southernmost extension of a large coronal hole (CH452) in the northern hemisphere will likely rotate into an Earth facing position on May 30-31.
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 very poor. Propagation on long distance northeast-southwest paths is fair to good.
The geomagnetic field is expected to be quiet to unsettled on May 30-31 due to effects from CH451 and quiet on June 1. Effects from CH452 could reach Earth on June 2 or 3 and cause unsettled to minor storm conditions.
|Coronal holes (1)||Coronal mass ejections (2)||M and X class flares (3)|
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.
(Click on image for higher resolution image) Compare to the previous day's image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.
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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with polarity overlay
|1||3||N17E67||0120||HSX||CSO||formerly region S1034
|3||10||S19E69||0080||CSO||DSI||formerly region S1036
|Total spot count:||30||87|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2010.02||84.7||18.8||10.6 (+1.3)||4.15 / 4.61|
|2010.03||83.4||15.4||12.3 (+1.7)||4.58 / 4.65|
|2010.04||75.9||8.0||14.0 (+1.7)||10.22 / 10.24|
|2010.05||73.8||8.7||15.5 (+1.5)||9.18 / 8.15|
|2010.06||72.5||13.6||16.4 (+0.9)||8.17 / 6.85|
|2010.07||79.8||16.1||16.7 (+0.3)||6.31 / 5.15|
|2010.08||79.2||19.6||17.4 (+0.7)||8.49 / 7.77|
|2010.09||81.1||25.2||19.6 (+2.2)||5.33 / 5.45|
|2010.10||81.6||23.5||23.2 (+3.6)||6.07 / 6.27|
|2010.11||82.5||21.5||(26.9 predicted, +3.7)||4.80 / 5.50|
|2010.12||84.2||14.4||(30.1 predicted, +3.2)||3.41 / 4.35|
|2011.01||83.6||19.1||(33.1 predicted, +3.0)||4.32 / 5.51|
|2011.02||94.6||29.4||(35.6 predicted, +2.5)||5.41 / 6.44|
|2011.03||115.0||56.2||(37.9 predicted, +2.3)||7.79|
|2011.04||112.6||54.4||(40.8 predicted, +2.9)||9.71|
|2011.05||94.7 (1)||54.2 (2A) / 57.9 (2B)||(44.1 predicted, +3.3)||(9.03)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official SIDC international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the preliminary 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 on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.