Solar Terrestrial Activity Report [Image] Last update September 27, 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 unsettled to active on September 26. Solar wind speed ranged between 509 and 676 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 223.6, the planetary A index was 21 (3-hour K indices: 4444 4433, Boulder K indices: 4344 4333). Region 9166 was quiet and stable but could still produce a minor M class flare while at the west limb today. Region 9167 was quiet and stable. Region 9169 decayed further and was quiet. The region is still capable of major flare production. Region 9170 developed slowly and could produce C and minor M class flares. Region 9171 was quiet and stable, as was region 9172. Region 9173 developed slowly and could produce C and minor M class flares. New region 9174 emerged in the southwest quadrant. New region 9175 rotated into view at the northeast limb. An active region with M class flare potential is rotating into view at the southeast limb and a couple of new regions are emerging in the northeast quadrant. Flares and CMEs A total of 6 C class events were recorded on September 26. Region 9173 produced a C4.3 flare at 12:31 and a C6.7 flare at 21:49 UTC. A filament eruption was observed to the north of region 9171 (in the southeast quadrant), the eruption began at 22:24 UTC as observed in LASCO EIT images. It is too early to tell if this eruption was accompanied by a potentially geoeffective CME. September 25: Region 9167 produced an M1.8 flare at 02:15 UTC, a weak halo CME associated with this event was observed by LASCO. This CME could impact Earth late on September 27 or early on September 28 and cause unsettled to minor storm conditions. 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 27 and quiet to minor storm on September 28. 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 no. Location at region numbered sunspots midnight Area Classification Comment 9166 20000914 10 S12W82 0370 DKI 9167 20000916 4 N16W55 0060 CSO 9169 20000918 67 N12W34 1210 FKC beta-gamma 9170 20000921 26 S05W38 0120 EAI 9171 20000922 4 S14E19 0070 CSO 9172 20000924 9 N12E46 0080 DSO 9173 20000924 10 S13E51 0120 EAO beta-gamma 9174 20000926 1 S30W60 0000 AXX 9175 20000926 2 N21E67 0030 CRO Total number of sunspots: 133 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 2000.09 179.7 (1) 132.8 (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]