Solar Terrestrial Activity Report [Image] Last update September 20, 2000 at 04:30 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 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update August 10, 2000)] Recent development The geomagnetic field was unsettled to major storm on September 19. Solar wind speed ranged between 569 and 828 km/sec. The interplanetary magnetic field swung southwards between 11:30 and 14h UTC and caused an increase in geomagnetic activity. Solar flare activity was high. Solar flux was 207.1, the planetary A index was 27 (3-hour K indices: 3335 6434, Boulder K indices: 3235 4223). Region 9161 decayed fairly quickly and was quiet, the region could become spotless in a day or two. Region 9165 decayed and is unlikely to produce further major flares. Region 9166 developed slowly and could produce a major flare. Region 9167 was mostly unchanged and may be capable of minor M class flaring. Region 9168 decayed into spotless plage. Region 9169 rotated fully into view revealing the largest sunspot group during solar cycle 23. M and X class flares are possible and the region has a magnetic delta configuration. Flares and CMEs A total of 6 C and 1 M class events were recorded on September 19. Region 9166 produced a C2.6 flare at 01:45, a C4.9 flare at 03:32 and a C3.0/1F flare at 15:19 UTC. Region 9165 generated a major M5.1/1N flare at 08:26 UTC. A weak type II sweep was associated with this event and a CME was observed in LASCO C3 several hours after the event. The CME seemed to be a partial halo one and could cause increased geomagnetic activity on September 22. 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 active on September 20-21. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor to useless. 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 9158 20000907 N31W87 plage 9161 20000911 1 N06W58 0010 AXX 9165 20000913 15 N15W54 0130 DAO beta-gamma 9166 20000914 33 S13E11 0670 DKC beta-gamma 9167 20000916 13 N12E41 0360 EAO 9168 20000917 N09W20 plage 9169 20000918 28 N09E60 2140 FKC beta-gamma-delta Total number of sunspots: 90 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.07 165.6 113.5 94.3 (+1.2) 1999.08 170.7 93.7 97.5 (+3.2) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.8 (+5.5) 1999.11 191.5 133.2 110.9 (+3.1) 1999.12 169.8 84.6 111.0 (+0.1) 2000.01 158.1 90.1 112.8 (+1.8) 2000.02 174.1 112.9 116.6 (+3.8) 2000.03 208.2 138.5 (118.7 predicted, +2.1) 2000.04 184.2 125.3 (119.6 predicted, +0.9) 2000.05 184.9 120.8 (120.4 predicted, +0.8) 2000.06 179.8 124.9 (122.0 predicted, +1.6) 2000.07 202.3 169.1 (124.1 predicted, +2.1) 2000.08 163.0 130.6 2000.09 163.3 (1) 81.6 (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]