Last major update issued on April 23, 2005 at 05:35 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update April 4, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 4, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 4, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update April 15, 2005)]
The geomagnetic field was quiet to unsettled on April 22. Solar wind speed ranged between 394 and 466 km/sec under the influence of a weak stream from CH159.
Solar flux measured at 20h UTC on 2.8 GHz was 77.2. The planetary
index was 9 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 22113232 (planetary), 23013232 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10752 was quiet and stable, the region will rotate out of view at the northwest limb late today and early
Region 10754 reemerged with a few spots.
Region 10755 decayed slowly and quietly.
April 20-22: No obvious fully or partly Earth directed CMEs were observed.
history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A coronal hole (CH160) in the southern hemisphere was in an Earth facing position on April 20. A small trans equatorial coronal hole (CH161) will be in an Earth facing position on April 23.
Processed SOHO/EIT 284 image at 01:06 UTC on April 22. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected be quiet to active on April 23 due to effects from CH160. Quiet is likely on April 24-25 while a few unsettled intervals could be observed on April 26 due to weak effects from CH161.
|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) Material from a CME is likely to impact 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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. At least 2 stations from Argentina were noted occasionally, as was CPN radio (Perú). Good signals near local sunrise were heard from Radio Córdoba (Argentina) on 700 and Rádio Sociedade (Brazil) on 740 kHz.
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|
|10755||2005.04.17||1||2||S11E09||0010||HSX||classification was AXX at midnight|
|Total spot count:||4||5|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.10||105.9||48.0||(35.6 predicted, -1.9)|
|2004.11||113.2||43.5||(33.9 predicted, -1.7)|
|2004.12||94.5||17.9||(31.6 predicted, -2.3)|
|2005.01||102.2||31.3||(28.9 predicted, -2.7)|
|2005.02||97.2||29.1||(26.5 predicted, -2.4)|
|2005.03||89.9||24.8||(24.7 predicted, -1.8)|
|2005.04||83.5 (1)||31.7 (2)||(22.9 predicted, -1.8)|
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% less.
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.