Solar Terrestrial Activity Report [Image] Last update September 18, 2001 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 1, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 1, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 1, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update July 27, 2001)] Recent development The geomagnetic field was quiet to unsettled on September 17. Solar wind speed ranged between 415 and 476 km/sec. Solar flare activity was high. Solar flux was 199.1, the planetary A index was 10 (3-hour K indices: 1233 3333, Boulder K indices: 1233 3333). Region 9608 was mostly unchanged and may be capable of producing another major flare before rotating out of view late today. Region 9610 decayed further and is rotating out of view. Region 9616 decayed slowly and is likely to produce further minor M class flares. Region 9617 was quiet and stable, as was region 9619. Regions 9620 and 9621 did not change much and may be capable of producing a minor M class flare. New regions 9622 and 9623 in the northeast quadrant were finally numbered. New region 9624 rotated into view at the northeast limb. Old region 9591 is about to rotate into view at the southeast limb. The region appears to be quite hot and could have major flare potential. Flares and CMEs A total of 11 C and 4 M class events were observed on September 17. Region 9608 produced a C3.6 flare at 06:53, a major impulsive M8.1/1N flare at 15:50, a C3.3/1F flare at 20:01 and an M1.0/2N flare at 21:46 UTC. Region 9616 generated an M1.5/2N flare (with an associated strong type II radio sweep and a partial halo CME originating from a nearby filament eruption triggered by the flare) and an M1.0/1N flare (with an associated moderate type II radio sweep) at 21:05 UTC. Region 9621 was the source of a C7.0 flare at 09:41 UTC. The background x-ray flux is at the class C1-C2 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 18-19. 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 9608 2001.09.05 10 S30W75 0420 EKI beta-gamma 9610 2001.09.06 6 S12W75 0150 DAO 9615 2001.09.08 N11W55 plage 9616 2001.09.11 25 S12E03 0270 FKI beta-gamma 9617 2001.09.12 4 N08E04 0020 CSO 9618 2001.09.13 S21W81 plage 9619 2001.09.13 2 N15W29 0020 CSO 9620 2001.09.16 2 N13E57 0180 HAX 9621 2001.09.16 3 N16E62 0130 CAO 9622 2001.09.17 5 N12E34 0040 DSO 9623 2001.09.17 1 N21E46 0020 HSX 9624 2001.09.17 1 N03E70 0040 HSX Total number of sunspots: 59 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.03 208.2 138.5 119.9 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.7 2000.08 163.0 130.5 118.6 (-1.1) 2000.09 182.1 109.7 116.3 (-2.3) 2000.10 167.4 99.4 114.5 (-1.8) 2000.11 178.8 106.8 112.8 (-1.7) 2000.12 173.6 104.4 112.1 (-0.7) 2001.01 166.6 95.6 108.8 (-3.3) 2001.02 146.6 80.6 104.1 (-4.7) 2001.03 177.7 113.5 (103.8 predicted, -0.3) 2001.04 177.7 108.2 (104.1 predicted, +0.3) 2001.05 147.1 97.3 (102.6 predicted, -1.5) 2001.06 173.0 134.0 (99.8 predicted, -2.8) 2001.07 131.3 82.2 (98.0 predicted, -1.8) 2001.08 162.9 106.8 (98.5 predicted, +0.5) 2001.09 221.6 (1) 114.8 (2) (97.5 predicted, -1.0) 1) Running average based on the daily 20:00 UT solar flux value at 2800 MHz. 2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]