Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update August 26, 1999 at 02:50 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 mostly quiet on August 25 with a single isolated active interval at the end of the day. Solar wind speed ranged between 491 and 635 km/sec. Solar flare activity was moderate. Solar flux was 208.4, the planetary A index was 8 (3-hour K indices: 2211 2224, Boulder K indices: 2211 2323). Region 8668 decayed slowly and was mostly quiet. The region will rotate off the visible disk early on August 27. Region 8673 was mostly quiet and stable. Region 8674 has 2 weak magnetic delta configurations, one in the trailing part of the region and another one near region center. The region is likely to generate further M class flares, an isolated X flare is possible as well. Regions 8675 and 8676 were quiet and stable. New region 8677 rotated partly into view at a low latitude on the northeast limb. New region 8678 emerged in the northwest quadrant. An active region is rotating into view at the southeast limb, it appears to be capable of at least C class flaring. Flares and CMEs A total of 7 C flares and 1 M flare were recorded on August 25. Region 8674 was the source of an impulsive M3.6/1N flare at 01:36 UTC. A weak type II sweep was observed just after the flare. A region on the backside of the northern hemisphere produced a large CME early in the day. Another backside CME was observed over the north pole early on August 26. 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 26-27. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is poor to 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 8668 990813 8 N23W75 0120 DAO 8673 990819 18 S21E08 0410 FKO 8674 990820 23 S24E11 0340 FAI beta-gamma 8675 990824 2 N18E66 0040 HSX 8676 990824 4 N26E61 0010 BXO 8677 990825 1 N07E71 0060 HSX 8678 990825 1 N16W40 0000 AXX Total number of sunspots: 57 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 160.0 (1) 95.8 (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]