Last major update issued on April 10, 2005 at 04:05 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 2, 2005)]
The geomagnetic field was quiet on April 9. Solar wind speed ranged between 294 and 338 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 88.4. The planetary
index was 4 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 21011221 (planetary), 12112322 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there were 4 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 10749 decayed slowly and quietly.
Region 10750 decayed early in the day and lost all spots outside the main penumbral area. Moderate development was observed late in the day with several new spots emerging and new penumbra forming. The region has mixed polarities. C flares are possible.
Region 10751 developed slowly. The region is magnetically a mess with several small areas of positive and negative polarity intermixing. C flares are possible.
Spotted regions not numbered by NOAA/SEC:
[S533] This region emerged on April 9 in the northeast quadrant near the central meridian and inside CH157. Several spots were visible at one point, however, the region was decaying slowly late in the day and only a single, small spot was visible at midnight. Location at midnight: N19W02.
April 7-9: 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 (CH157) in the northern hemisphere will be in an earth facing position on April 9-10.
Processed SOHO/EIT 284 image at 01:06 UTC on April 10. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet on April 10-11 and quiet to active on April 12-13 due to effects from CH157..
|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 fair. 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). The best reception from North America was of CJYQ 930, VOWR 800 and KNR on 650 kHz, all with fair signals.
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|
area was 0050 at midnight
|Total spot count:||13||17|
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||85.0 (1)||13.4 (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.