Last major update issued on May 24, 2010 at 04:35 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 2, 2010)]
The geomagnetic field was very quiet on May 23. Solar wind speed ranged between 345 and 391 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 74.5. The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.4). Three hour interval K indices: 10000111 (planetary), 01000101 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight there was 1 spotted region on the visible solar disk.
Region 11072 decayed significantly and appears to be losing the trailing spots.
May 21-22: No obvious Earth directed CMEs were observed in LASCO or
May 23: At least a partial halo CME was observed in STEREO 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 small coronal hole (CH405) in the southern hemisphere rotated across the central meridian on May 20. A well defined recurrent coronal hole in the northern hemisphere is currently near the east limb.
Processed SOHO/EIT 195 image at 00:00 UTC on May 24. 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.
The geomagnetic field is expected to be initially quiet on May 24. Later in the day and on May 25 quiet to unsettled conditions are possible due to weak effects from CH405. Late on May 26 or early on May 27 quiet to active conditions are possible as a CME observed on May 23 could reach Earth.
|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
|11072||2010.05.21||13||8||S15W09||0130||DSI||classification was DSO at midnight, area 0090|
|Total spot count:||13||8|
|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||74.1 (1)||13.5 (2)||(16.6 predicted, +1.3)||(8.26)|
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.