Last major update issued on May 7, 2007 at 04:45 UTC. Minor update posted at 11:33 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update May 6, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update May 6, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update May 6, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update April 7, 2007)]
The geomagnetic field was very quiet on May 6. Solar wind speed ranged between 271 and 286 km/s (average speed was 276 km/s, decreasing 16 km/s from the previous day). Solar wind speed increased somewhat after 21h UTC. As I write this solar wind density is increasing slowly as the disturbance associated with CH268 is approaching Earth.
Solar flux measured at 20h UTC on 2.8 GHz was 78.1. The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.1). Three hour interval K indices: 10000111 (planetary), 00010211 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.
Region 10953 decayed slowly and was mostly quiet. Flare: C1.1 at 23:19 UTC.
Comment added at 11:33 UTC on May 7: A minor solar wind shock was observed at SOHO at 07:47 UTC with a sudden increase in wind speed from 275 to 328 km/s. Solar wind density became very high after the arrival of a CME associated with the C8.5 flare in region 10953 on May 2. Currently solar wind speed is approaching 400 km/s and it is difficult to tell whether the CME or a low speed stream from CH268 is the major contributor to the solar wind. Should the interplanetary magnetic field swing significantly southwards minor geomagnetic storming will become possible.
May 4-6: No obvious fully or partially Earth directed CMEs were observed in LASCO imagery.
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 recurrent coronal hole (CH268) in the southern hemisphere was in an Earth facing position on May 3-4.
Processed SOHO/EIT 195 image at 00:00 UTC on May 7. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on May 7-8 due to effects from CH268 and quiet on May 9-11.
|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.
Daily monitoring will not resume until a local noise problem (related to construction work on a neighboring property) has been fixed. Occasional monitoring reports will be submitted when propagation is good.
April 8, 2007: Stations from the Canadian Atlantic provinces had strong signals during the night. Some stations from the northeastern USA and from Florida did well too, in particular 1510 WWZN was impressive.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. 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 SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
|Active region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
|10953||2007.04.25||4||3||S10W69||0120||CAO||classification was HAX at midnight|
|Total spot count:||4||3|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2006.11||86.3||21.5||(12.4 predicted, -1.8)|
|2006.12||84.5||13.6||(11.3 predicted, -1.1)|
|2007.01||83.3||16.9||(10.6 predicted, -0.7)|
|2007.02||77.7||10.6||(10.3 predicted, -0.3)|
|2007.03||72.2||4.8||(10.3 predicted, +0.0)|
|2007.04||72.4||3.7||(10.8 predicted, +0.5)|
|2007.05||83.1 (1)||4.8 (2)||(10.9 predicted, +0.1)|
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/SEC) 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.