sunspot 930 a go-go

**aleceppi** · 09/12/2006, 16:52

Eccezionali Mory!

**Lorenzo Catania** · 14/12/2006, 11:26

Altra esplosione solare piuttosto forte (X3)

Notare anche la velocità del vento solare, superiore ai 2 milioni di km/h

Recent activity

The geomagnetic field was quiet to unsettled on December 13. Solar wind speed ranged between 568 and 767 km/s (all day average 618 km/s - decreasing 83 km/s from the previous day) under the influence of a high speed stream from CH251.
Solar flux measured at 20h UTC on 2.8 GHz was 93.6. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 23000002 (planetary), 34112112 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was high. A total of 2 C and 1 X class events was recorded during the day.
Region 10930 developed slowly in the southern part of the main penumbra as a few positive polarity spots emerged while slow decay was observed in the northern negative polarity section. Further major flares are possible as long as the current magnetic delta structure persists. Flares: major X3.4/4B proton flare peaking at 02:40, C2.2 at 14:23 and C1.7 at 18:25 UTC.

Coronal mass ejections (CMEs)

December 11-12: No obvious partly or fully Earth directed CMEs were detected in LASCO imagery.
December 13: A fast full halo CME was observed shortly after the X3 flare.
Coronal holes

Coronal hole 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
Recurrent coronal hole CH252 (southern hemisphere) will likely rotate into an Earth facing position on December 16-17.

Processed SOHO/EIT 284 image at 01:38 UTC on December 14. The darkest areas on the solar disk are likely coronal holes.
Forecast

The geomagnetic field is expected to be quiet initially on December 14, then, sometime during the latter half of the day and on December 15, range from active to severe storm conditions due to CME effects. Quiet to active conditions are likely on December 16.
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.
Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation on long distance northeast-southwest paths is very poor.
Monitoring remarks from a location near N58E06: No North American stations were heard. A few of the more common Puerto Rican stations (1320 Radio Isla and 1480 Onda Tropical) and 1290 Radio Puerto Cabello (Venezuela) were present; otherwise another very poor night for TA signals.