Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 23, 1999 at 04:30 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 22. Solar wind speed ranged between 281 and 337 km/sec. Solar flare activity was high. Solar flux was 201.7, the planetary A index was 2 (3-hour Kp indices: 0000 1111, Boulder K indices: 0000 0100). Region 8798 decayed slowly and was mostly quiet. The region is still complex and capable of M class flaring. Region 8803 developed slowly and could produce further C class flares. Region 8804 was quiet and stable. Region 8806 is a large, complex region capable of producing major flares. Further major flares are possible, perhaps even a proton flare. Region 8807 is unstable and could produce further C flares or even minor M flares. Flares and CMEs 5 C flares and 2 M flares were recorded on December 22. Region 8803 produced a C4.3 flare at 00:10 UTC and a C3.1 flare at 13:54 UTC. Region 8806 was the source of a major flare, an impulsive M5.3/1B event at 19:04 UTC. A halo CME was observed in LASCO C2 starting at 19:31 UTC. Although there is a possibility the CME could be related to backside activity, it was likely a result of the activity in region 8806. There is a fair chance the CME could impact Earth on December 25 or 26. Region 8807 generated a C2.7 flare at 01:21 UTC and an M1.8/2B event at 02:16 UTC. The flare was preceded by a filament eruption to the north of the region. This eruption was associated with a moderately strong type II sweep and a coronal mass ejection off the north pole and the northeast limb. The background x-ray flux is at the class B8 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be mostly quiet on December 23-24. There is a chance of a CME impact on Dec.25 or 26. Should that happen, unsettled to minor storm would be likely. 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 30 S13W47 0350 EKI beta-gamma-delta 8800 991214 N10W48 plage 8802 991216 S23W74 plage 8803 991216 6 S14W57 0050 DAO 8804 991216 1 S18E02 0240 HSX 8806 991217 37 N19E12 1050 FKC beta-gamma 8807 991218 6 N10E16 0030 DAO 8808 991219 S18W34 plage Total number of sunspots: 80 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 173.0 (1) 89.6 (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]