Solar Terrestrial Activity Report [Image] Last update September 30, 2000 at 04:30 UTC. Minor update posted at 07:32 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 unsettled on September 29. Solar wind speed ranged between 329 and 431 km/sec. Solar flare activity was low. Solar flux was 192.0, the planetary A index was 7 (3-hour K indices: 3212 2222, Boulder K indices: 1212 2201). Region 9169 decayed further and was quiet, the region will be rotating off the visible disk today and early tomorrow, isolated M class flares are still possible. Region 9170 was quiet and stable and will rotate over the west limb today. Regions 9171 and 9172 were quiet and stable. Region 9173 developed slowly and could produce C and minor M class flares. Region 9175 was quiet and stable. Region 9176 developed further and has M class flaring potential. The magnetic field within the region is unusually confused and the region has a good potential for further development. Region 9177 was quiet and stable. Region 9178 developed slowly and could produce C flares. Comment added at 07:32 UTC on September 30: A minor solar wind shock was observed at ACE at 04:20 UTC. The interplanetary magnetic field swung moderately to strongly southwards. Currently the geomagnetic field is at active to minor storm levels. Flares and CMEs A total of 8 C class events were recorded on September 29. Region 9173 produced a C2.2 flare at 00:45, a C5.9/1F flare at 06:57, a C1.9 flare at 16:44 and a C2.8 flare at 20:51 UTC. Region 9178 generated a C3.4 flare at 03:21 while region 9176 managed a C3.0 flare at 10:17 UTC. September 28: A filament eruption was observed to the south and east of region 9177 across the central meridian. The eruption began at 04:24 UTC as observed in LASCO EIT images. A weak, possibly full halo CME was observed associated with this event. The CME could impact Earth sometime between late on September 30 and noon on October 1 and cause unsettled to minor storm conditions. September 27: A large filament eruption began at 19:48 UTC in the southeast quadrant covering an area from near region 9173 to near the central meridian. A dense CME was observed off parts of the southeast and southwest limbs and the south pole, this CME was probably a partial halo CME and could affect the geomagnetic field on September 30 or October 1. The background x-ray flux is at the class C1 level. Coronal holes A small coronal hole near the equator will rotate into a geoeffective position on September 29 and could cause the geomagnetic field to become unsettled to active on October 2. Forecast The geomagnetic field is expected to be unsettled to minor storm on September 30 and October 1. 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 9169 20000918 10 N12W77 0720 EKC beta-gamma 9170 20000921 4 S05W79 0030 CRO 9171 20000922 4 S13W22 0040 CSO 9172 20000924 5 N12E08 0050 CSO 9173 20000924 25 S12E13 0220 EAI beta-gamma 9175 20000926 2 N22E32 0000 AXX 9176 20000927 16 S09E45 0410 EAO beta-gamma 9177 20000927 3 N30W23 0010 BXO 9178 20000928 5 S22E49 0050 CAO Total number of sunspots: 111 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 2000.09 181.7 (1) 153.0 (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]