Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 7, 1999 at 04:05 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update December 2, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update December 2, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 1999)] [Historical solar and geomagnetic data charts 1954-1999] [Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was quiet to active on December 6 under the influence of a high speed coronal stream. Solar wind speed ranged between 548 and 727 km/sec. Solar flare activity was low. Solar flux was 142.8, the planetary A index was 19 (3-hour Kp indices: 2444 4332, Boulder K indices: 2344 4432). Region 8781 was quiet and stable, the region rotated off the visible disk early today. Region 8785 was quiet and stable. Region 8787 developed slowly and was mostly quiet. Region 8788 developed a weak magnetic delta configuration near the large trailing spot. Further C class flaring is very likely and the region has a fair chance of generating an M flare as well. Region 8789 once again decayed into spotless plage. New region 8790 emerged in the northeast quadrant. An active region at the southeast limb should rotate into view today and tomorrow. Flares and CMEs 8 C flares were recorded on December 6 with region 8788 the source of all optically assigned flares. The region produced a C8.4 flare at 07:18 UTC. It was accompanied by a type II sweep and a full halo coronal mass ejection. This CME has a high probability of impacting Earth sometime on December 9 or early on Dec.10. Region 8788 also produced a long duration C4.9 event peaking at 22:08 UTC and an impulsive C8.7 flare at 01:12 UTC on December 7. The background x-ray flux is at the class B8 level. Coronal holes A large trans equatorial coronal hole was in a geoeffective position on December 1-5. Forecast The geomagnetic field is expected to be quiet to minor storm December 7-8. Unsettled to major storm is expected on December 9 as a CME is likely to impact Earth. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally poor to very poor. Coronal holes (1) Coronal mass M and X class flares (3) ejections (2) [Coronal hole indicator][CME indicator] [M and X class flare indicator] 1) Effects from a coronal hole could reach earth within the next 5 days. 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. Active solar regions (Recent map) Solar Date Actual Location region numbered no. at Area Classification Comment sunspots midnight 8781 991124 2 S12W88 0050 CAO 8784 991130 N30W47 plage 8785 991201 4 N13E05 0130 CAO 8786 991202 N22W65 plage 8787 991202 3 N11W08 0020 DSO 8788 991202 17 N09E29 0550 FKO beta-gamma-delta 8789 991202 N29W61 8790 991206 4 N09E47 0020 BXO Total number of sunspots: 30 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 9810 117.2 55.5 70.5 (+1.0) 9811 140.1 74.0 73.0 (+2.5) 9812 150.1 81.9 77.9 (+4.9) 9901 140.6 62.0 82.6 (+4.7) 9902 141.9 66.3 84.6 (+2.0) 9903 126.3 68.8 83.8 (-0.8) 9904 117.2 63.7 85.4 (+1.6) 9905 148.4 106.4 90.4 (+5.0) 9906 169.8 137.7 (94.4 predicted, +4.0) 9907 165.6 113.5 (99.4 predicted, +5.0) 9908 170.7 93.7 (105.3 predicted, +5.9) 9909 135.7 70.6 9910 164.8 116.4 9911 191.5 132.7 9912 152.6 (1) 19.9 (2) 1) Running average based on the daily 20:00 UTC solar flux measurement at 2800 MHz by DRAO. 2) Unofficial, accumulated value. The official value is typically 25-40% less. This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]