Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update September 10, 1999 at 04:10 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update September 1, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 1, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 1, 1999)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to unsettled on September 9. Solar wind speed ranged between 386 and 456 km/sec. Solar flare activity was low. Solar flux was 106.5 (lowest index since April 26, 1999. At 23h UTC solar flux was 104.6), the planetary A index was 8 (3-hour K indices: 3122 3322, Boulder K indices: 3122 3222). Region 8682 was quiet and stable and is rotating off the visible disk. Region 8689 was quiet and stable. Region 8690 developed a few more spots but lost its magnetic delta configuration. Further C class flares are likely. Region 8691 was quiet and stable. Region 8692 developed a magnetic delta configuration. Minor M class flares are possible. Regions 8693 and 8694 were quiet and stable. An active region is rotating into view at the northeast limb. A new region appears to be developing near region 8693. Flares and CMEs Region 8690 produced the only flare on September 9, a long duration C3.3 event at 16:37 UTC. A full halo CME from a back side source was observed in LASCO C3 after 14h UTC. The background x-ray flux is at the class B2 level. Coronal holes A coronal hole in the northern hemisphere was in a geoeffective position on September 8-10. A moderately large and well placed coronal hole in the southern hemisphere will rotate into a geoeffective position on September 10-12. Forecast The geomagnetic field is expected to be quiet to active on September 10. A coronal stream will likely arrive on September 11 or 12 and cause unsettled to active conditions, possibly even minor storming. Another coronal stream should arrive on September 13 and cause unsettled to minor storm conditions, possibly with isolated major storm intervals. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally fair. 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 8682 990829 3 N18W85 0030 CRO 8684 990830 S14W79 plage 8685 990831 S08W50 plage 8688 990903 S24W66 plage 8689 990905 3 N20W61 0010 AXX 8690 990906 14 N13E33 0040 CSO beta-gamma 8691 990907 5 S29W58 0010 BXO 8692 990907 12 S26E48 0340 DAO beta-gamma-delta 8693 990907 1 N12E51 0070 HSX 8694 990908 5 S16W27 0010 BXO Total number of sunspots: 43 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 62.0 82.6 (+4.7) 9902 141.9 66.3 84.6 (+2.0) 9903 126.3 68.8 (85.0 predicted, +0.4) 9904 117.2 63.9 (88.0 predicted, +3.0) 9905 148.4 106.4 (93.4 predicted, +5.4) 9906 169.8 137.4 9907 165.6 113.5 9908 170.7 93.7 9909 128.4 (1) 33.5 (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]