Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update August 22, 1999 at 04:50 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update August 2, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update August 2, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update August 2, 1999)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet on August 21. Solar wind speed ranged between 454 and 583 km/sec. Solar flare activity was high. Solar flux was 161.2, the planetary A index was 6 (3-hour K indices: 1222 2222, Boulder K indices: 1323 2210). Region 8668 was quiet and stable but could produce isolated C flares and perhaps even a minor M class flare. Region 8672 decayed further and is spotless early on August 22. Region 8673 was mostly quiet and stable. The region has M class flaring potential. Region 8674 continued to produce M flares. Further M flares and occasional X flares are likely. Flares and CMEs A total of 5 C class events and 2 M flares were observed on August 21. Region 8674 was the origin of both M flares. An impulsive M3.7/1B flare was observed at 16:34 UTC. It was accompanied by a moderately strong type II sweep and a small CME off the southeast limb. At 22:14 UTC a major M5.9/1N impulsive flare occurred, no coronal mass ejection was observed. 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 quiet to unsettled on August 22. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is 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 no. Location at region numbered sunspots midnight Area Classification Comment 8665 990811 S26W66 plage 8667 990812 N24W46 plage 8668 990813 11 N22W25 0230 CHO 8669 990814 S21W52 8672 990818 2 N16W49 0010 AXX 8673 990819 16 S19E55 0400 FHO 8674 990820 10 S25E60 0400 FAO Total number of sunspots: 39 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 9807 114.0 66.6 65.5 (+3.0) 9808 136.0 92.2 67.8 (+2.3) 9809 138.3 92.9 69.5 (+1.7) 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 62.4 82.6 (+4.7) 9902 141.9 66.1 (85.6 predicted, +3.0) 9903 126.3 69.1 (87.6 predicted, +2.0) 9904 117.2 63.9 (91.2 predicted, +3.6) 9905 148.4 106.3 9906 169.8 137.4 9907 165.6 113.5 9908 153.8 (1) 82.4 (2) 1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz.. 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]