Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update August 30, 1999 at 03:35 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 to unsettled on August 29. Solar wind speed ranged between 508 and 704 km/sec. Solar flare activity was low. Solar flux was 218.2, the planetary A index was 10 (3-hour K indices: 2223 2333, Boulder K indices: 2222 1222). Region 8673 was quiet and stable. Region 8674 lost some spots and the magnetic delta in the trailing part of the region weakened. The region could be slowly decaying. Further M flares are possible but the chance of an X flare has decreased significantly. Region 8675 developed slowly and has M class flaring potential. Region 8676 was quiet and stable. Regions 8677 and 8679 were quiet and stable. Region 8678 rotated off the visible disk. Region 8681 developed quickly but not as fast as on the previous day. M class flares are possible over the next days. New region 8682 rotated into view at the northeast limb. Flares and CMEs A total of 5 C flares (1 from region 8674, 2 from region 8675 and 1 from region 8681) was recorded on August 29. Region 8681 produced the most significant event of the day, a C9.6/1N flare at 17:31 UTC. August 28: Region 8674 was the source of an X1.1 moderate duration major flare which peaked at 18:05 UTC. It was accompanied by a strong type II sweep and a large coronal mass ejection. At least a partial halo CME was observed in LASCO images with the densest part of the CME below the south pole. A terrestrial impact is likely sometime from early on August 31 to early on September 1 but is not likely to create a disturbance beyond the active to minor storm levels. The background x-ray flux is at the class C1-C2 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 30 and quiet to active with possible minor storm intervals on August 31. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is fair to 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 Location region numbered no. at Area Classification Comment sunspots midnight 8673 990819 2 S19W51 0290 HHX 8674 990820 69 S23W39 0700 FAC beta-gamma-delta 8675 990824 28 N20E14 0210 DSI 8676 990824 6 N26E08 0020 BXO 8677 990825 5 N08E20 0070 CSO 8679 990826 9 S34E22 0020 BXO 8681 990828 29 N21W04 0220 DAI 8682 990829 1 N18E65 0040 HSX Total number of sunspots: 149 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 (84.9 predicted, +2.3) 9903 126.3 69.1 (86.4 predicted, +1.5) 9904 117.2 63.9 (90.0 predicted, +3.6) 9905 148.4 106.3 9906 169.8 137.4 9907 165.6 113.5 9908 169.4 (1) 123.1 (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]