Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 21, 1999 at 03:55 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 20. Solar wind speed ranged between 354 and 423 km/sec. Solar flare activity was low. Solar flux was 209.2, the planetary A index was 3 (3-hour Kp indices: 0011 0211, Boulder K indices: 0012 2222). Region 8797 decayed into spotless plage. Region 8798 was mostly quiet and unchanged. It is still a complex region capable of M class flaring. The region appears to have peaked and will likely decay slowly. Region 8803 decayed slowly and was quiet. Region 8804 was quiet and stable. Region 8806 is a large region capable of producing major flares. It developed a magnetic delta configuration, however, the region appears to have peaked in its development. M class flares are possible. Region 8807 is likely to produce further C flares. Region 8808 was quiet and stable, the region appears to be spotless early on Dec.21. Flares and CMEs 9 C flares were recorded on December 20. Region 8807 produced 2 C flares, the largest was a C3.3 flare at 15:16 UTC. Region 8806 was the source of 3 C flares, the largest being C2.5 flares at 16:07 and 22:32 UTC. The most energetic flares of the day, C4 events at 01:08, 01:44 and 04:13 UTC, were all optically uncorrelated. A large and fast halo CME from a region 5-6 days behind the northeast limb was observed starting at 18:06 UTC in LASCO C2 images. The background x-ray flux is at the class C1 level. Coronal holes A weak coronal hole in the northern hemisphere may have been in a geoeffective position on December 18-20. Forecast The geomagnetic field is expected to be mostly quiet on December 21. Quiet to unsettled is possible on December 22-23. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally 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 8792 991208 N20W89 plage 8794 991209 S16W79 plage 8797 991213 S32W78 plage 8798 991213 43 S14W21 0460 EAI beta-gamma-delta 8800 991214 N10W22 plage 8801 991214 S22W78 plage 8802 991216 S23W48 plage 8803 991216 8 S13W31 0030 DSO 8804 991216 2 S20E29 0290 CHO 8805 991217 N18W67 plage 8806 991217 28 N19E37 1040 FKI beta-gamma-delta 8807 991218 6 N10E44 0040 CAO 8808 991219 2 S18W08 0000 AXX Total number of sunspots: 89 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 169.4 (1) 81.2 (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]