Solar Terrestrial Activity Report [Image] Last update September 26, 2000 at 04:25 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 quiet to active on September 25. Solar wind speed ranged between 435 and 597 km/sec under the influence of a coronal stream. Solar flare activity was moderate. Solar flux was 225.6, the planetary A index was 16 (3-hour K indices: 2234 4334, Boulder K indices: 2234 2323). Region 9166 decayed slowly but could still produce occasional minor M class flares, the region will rotate off the visible disk on September 27. Region 9167 was mostly quiet and stable. Region 9169 decayed fairly quickly. Although this is still a large region the potential for very energetic flares is less than it has been over the last few days. Region 9170 was mostly unchanged and quiet. Region 9171 was quiet and stable. Region 9172 developed slowly and could produce C flares. Region 9173 was quiet and stable. Flares and CMEs A total of 4 C and 2 M class events were recorded on September 25. Region 9166 was the source of an M3.4/1N flare at 00:53. Region 9167 produced an M1.8 flare at 02:15 UTC, a weak halo CME was observed by LASCO. This CME could impact Earth late on September 27 or early on September 28. Region 9169 generated a C2.2 flare at 12:54 UTC. September 23: Region 9169 produced a C8.6/1F flare at 21:42 UTC. LASCO C2 and C3 images indicate a full halo CME may have been associated with this event. The CME could impact Earth late on September 26 or early on the 27th. The background x-ray flux is at the class C1 level. Coronal holes No obvious coronal holes are approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to active on September 26. There is a possibility of a CME impact late on September 26 or early on the 27 and this could cause geomagnetic activity to reach minor or perhaps even major storm levels. Long distance medium wave (AM) band 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 9166 20000914 23 S12W70 0380 DAI 9167 20000916 5 N15W42 0080 CSO 9169 20000918 88 N11W22 1450 FKC beta-gamma-delta 9170 20000921 19 S06W27 0080 DAO 9171 20000922 3 S15E33 0080 CSO 9172 20000923 6 N12E58 0100 DAO 9173 20000923 1 S13E60 0070 HSX Total number of sunspots: 145 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 2000.09 177.9 (1) 125.0 (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]