Last major update issued on April 19, 2005 at 04:050 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 18. Solar wind speed ranged between 345 and 382 km/sec, most of the day under the influence of a weak low speed stream from CH158.
Solar flux measured at 20h UTC on 2.8 GHz was 81.3. The planetary
index was 8 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 13212222 (planetary), 23313432 (Boulder).
The background x-ray flux is at the class A5 level.
At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was low. No C class events were recorded during the day.
Region 10752 was quiet and did not display significant changes.
Region 10754 decayed slowly and quietly.
Region 10755 was mostly unchanged and quiet.
April 16-18: 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 recurrent coronal hole (CH158) in the southern hemisphere was in an Earth facing position on April 15-17. A coronal hole (CH159) in the northern hemisphere will be in an Earth facing position on April 19-20. A coronal hole (CH160) in the southern hemisphere will be in an Earth facing position on April 20.
Processed SOHO/EIT 284 image at 01:06 UTC on April 19. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected be quiet to active by on April 19-20 due to a low speed stream from CH158. Quiet to unsettled is likely on April 21 becoming quiet to active on April 22-23 due to effects from CH159 and CH160.
|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 to very poor. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with a weak signal. Only a few stations from North America were noted with weak signals: 930 CJYQ, 1400 CBG and 1510 WWZN.
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|
|10754||2005.04.14||4||5||S07E00||0030||CSO||classification was CRO at midnight, area 0010|
|10755||2005.04.17||1||2||S11E67||0040||HAX||classification was HSX at midnight, area 0020|
|Total spot count:||14||13|
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||84.9 (1)||27.1 (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.