Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update August 29, 1999 at 04:05 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 28. Solar wind speed ranged between 540 and 731 km/sec, still under the influence of a high speed coronal stream Solar flare activity was high. Solar flux was 248.4 (the highest solar flux value during solar cycle 23 for the third consecutive day), the planetary A index was 13 (3-hour K indices: 3233 3333, Boulder K indices: 2233 4431). Region 8673 decayed and was quiet. Region 8674 is still developing and is approaching 100 spots early on August 29. The region is likely to produce further M and X class flares over the next days, particularly if the magnetic delta in the trailing end of the region persists. Region 8675 is developing slowly and has M class flaring potential. Region 8676 produced several C flares, possibly due to its proximity to region 8675. Regions 8677, 8678 and 8679 were quiet and stable. New region 8681 emerged in the northeast quadrant to the west of region 8676. The region is developing very quickly (the fastest spot development rate observed during solar cycle 23) and has a weak magnetic delta configuration. M class flares are likely from region 8681 with an X class flare a possibility should the current rate of development continue. Flares and CMEs A total of 4 C flares, 1 M flare and 1 X flare were recorded on August 28 with both the larger events occurring in region 8674. An M2.8 flare was observed at 01:02 UTC. An X1.1 moderate duration major flare peaked at 18:05 UTC (the flare was initially attributed to region 8681 by SEC/NOAA). 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 29-30 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 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 3 S23W38 0370 CHO 8674 990820 87 S24W28 0730 FKC beta-gamma-delta 8675 990824 18 N20E27 0130 DSO 8676 990824 4 N26E20 0010 BXO 8677 990825 5 N08E33 0070 CSO 8678 990825 1 N15W81 0000 AXX 8679 990826 4 S34E31 0040 CAO 8681 990828 23 N21E08 0050 DSO Total number of sunspots: 145 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 167.7 (1) 115.7 (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]