Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 22, 1999 at 05:25 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 on December 21. Solar wind speed ranged between 333 and 386 km/sec. Solar flare activity was moderate. Solar flux was 217.2, the planetary A index was 2 (3-hour Kp indices: 0011 1101, Boulder K indices: 1012 1111). Region 8798 decayed slowly and was mostly quiet. The region is still complex and capable of M class flaring. Region 8803 was mostly quiet and stable, as was region 8804. Region 8806 is a large, complex region capable of producing major flares. Further M class flares are possible, as is a major M or X class flare. Region 8807 was mostly quiet and stable. Region 8808 decayed into spotless plage. Flares and CMEs 4 C flares and 1 M flare were recorded on December 21. Region 8803 produced a C3.4 flare at 23:38 UTC. Region 8798 was the source of a C2.0 flare at 10:35 UTC. Region 8806 generated a C3.2 flare at 01:09 UTC and an impulsive M1.1/1N flare at 17:19 UTC. Flare activity increased early on Dec.22. A filament eruption in a spotless plage region north of region 8806 triggered an event level flare in that region. This again triggered an M1.8 flare in region 8807 at 02:16 UTC. The flare was accompanied by a moderately strong type II sweep. There is a slight possibility the associated CME could be geoeffective. The background x-ray flux is at the class C1 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be mostly quiet on December 22-23. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally fair to good. 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 8798 991213 31 S13W33 0450 EKC beta-gamma-delta 8800 991214 N10W35 plage 8802 991216 S23W61 plage 8803 991216 7 S13W43 0020 BXO 8804 991216 1 S18E15 0280 HHX 8805 991217 N18W80 plage 8806 991217 33 N19E24 0940 FHC beta-gamma-delta 8807 991218 7 N11E29 0030 CSO 8808 991219 S18W21 plage Total number of sunspots: 79 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 (92.5 predicted, +2.1) 9907 165.6 113.5 (94.0 predicted, +1.5) 9908 170.7 93.7 (98.9 predicted, +4.9) 9909 135.7 70.6 9910 164.8 116.4 9911 191.5 132.7 9912 171.6 (1) 85.4 (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]