Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 10, 1999 at 04:20 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 9 under the influence of a high speed coronal stream. Solar wind speed ranged between 489 and 584 km/sec. Solar flare activity was low. Solar flux was 156.2, the planetary A index was 12 (3-hour Kp indices: 3433 2333, Boulder K indices: 3433 2233). Region 8785 decayed slowly and was quiet. Region 8787 was quiet and stable, the region is showing signs of development early on Dec.10. Region 8788 was quiet and stable. The region has minor M class flaring potential. Region 8790 developed slowly and was mostly quiet. Region 8791 was quiet and is decaying. It could become spotless today or tomorrow. Region 8792 was quiet and stable. New region 8793 emerged in the southeast quadrant and is likely capable of producing C flares. New region 8794 rotated into view at the southeast limb. Further active regions will rotate into view over the next few days. A new region is developing rapidly in the southeast quadrant near region 8793. This region could become capable of C class flaring today. Flares and CMEs 6 C flares were recorded on December 9. Region 8794 produced a C2.2 flare at 19:58 UTC, the remaining flares were optically unaccounted. December 6: Region 8788 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 could impact Earth during the first half of Dec.10. The background x-ray flux is at the class B6 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on December 10. If the CME observed on Dec.6 impacts Earth today, 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 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 no. Location at region numbered sunspots midnight Area Classification Comment 8784 991130 N30W86 plage 8785 991201 2 N14W35 0110 CSO 8787 991202 1 N13W48 0010 HSX 8788 991202 13 N10W10 0560 FHO 8790 991206 10 N11E07 0050 DSO 8791 991207 2 S14E36 0010 BXO 8792 991208 1 N16E56 0080 HSX 8793 991209 8 S16E11 0010 BXO 8794 991209 1 S15E58 0050 HSX Total number of sunspots: 38 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 (93.6 predicted, +3.2) 9907 165.6 113.5 (96.9 predicted, +3.3) 9908 170.7 93.7 (102.8 predicted, +5.9) 9909 135.7 70.6 9910 164.8 116.4 9911 191.5 132.7 9912 152.8 (1) 29.2 (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]