Last major update issued on May 1, 2006 at 05:20 UTC.
geomagnetic data - last month (updated daily)]
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The geomagnetic field was inactive to very quiet on April 30. Solar wind speed ranged between 282 and 355 (all day average 292) km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 99.9. The planetary A index
was 1 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 00000001 (planetary), 00000010 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.
Region 10875 decayed slowly and quietly.
Region 10876 decayed in the trailing spot section. Some new small spots were observed in the leading spot section. Flare: C1.8 at 09:32 UTC.
New region 10878 rotated into view at the northeast limb on April 29 and was numbered the next day by SEC. Flare: C5.3 at 01:57 UTC.
April 28-30: No partly or fully Earth directed CMEs were observed in LASCO imagery.
Coronal hole 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 trans equatorial coronal hole (CH222) will likely rotate into an Earth facing position on May 3-4.
Processed SOHO/EIT 284 image at 13:06 UTC on April 30. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet on May 1-3.
|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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Vibración (Venezuela) and CPN Radio (Perú) had the best signals. On other frequencies a number of stations from the Canadian Atlantic provinces and the US east coast were audible before LSR. After LSR propagation was best to Argentina.
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|
|10875||2006.04.23||20||16||S08W21||0340||EKI||classification was CKI at midnight|
|10878||2006.04.26||3||3||N14E60||0060||BXO||formerly region S648
classification was HAX at midnight
|Total spot count:||32||30|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2005.10||77.0||8.5||(24.8 predicted, -1.0)|
|2005.11||86.3||18.0||(22.7 predicted, -2.1)|
|2005.12||90.7||41.2||(19.8 predicted, -2.9)|
|2006.01||83.4||15.4||(16.7 predicted, -3.1)|
|2006.02||76.5||4.7||(13.6 predicted, -3.1)|
|2006.03||75.4||10.8||(11.4 predicted, -2.2)|
|2006.04||89.0 (1)||55.2 (2)||(10.7 predicted, -0.7)|
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.