Solar Terrestrial Activity Report [Image] Last update October 19, 2001 at 04:35 UTC. Last minor update posted at 12:47 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update October 3, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update October 3, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update October 3, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update October 16, 2001)] Recent development The geomagnetic field was quiet to unsettled on October 18. Solar wind speed ranged between 291 and 332 km/sec. Solar flare activity was low. Solar flux was 228.7, the planetary A index was 4 (3-hour K indices: 0001 2321, Boulder K indices: 1101 2331). Region 9658 decayed slightly but could still produce another minor M class flare. Region 9661 decreased in areal coverage but still has two magnetic delta structures. The region could produce further major flares. Region 9662 decayed slowly and quietly. Region 9667 was quiet and stable. Region 9669 developed slowly and could produce minor M class flares. Region 9670 developed slowly, occasional minor M class flares are possible. Region 9671 developed slowly and quietly. New region 9672 rotated into view at the southeast limb and may be capable of M class flare production. New region 9673 rotated into view at the northeast limb. Comment added at 09:44 UTC on October 19: Another major flare is in progress and has just peaked at the M5.7 level. Its source was likely in region 9661. An M1.3 flare peaked at 06:45 earlier today, its source was in region 9671, a region which has developed quickly today and has mixed magnetic polarities. Comment added at 12:47 UTC: The X flare early today was associated with a full halo CME. The CME will impact Earth, probably late on October 20 or during the first half of October 21. The M5.7/1B flare at 09:43 UTC was located in region 9658. No large CME appears to have been associated with this event. A minor disturbance was observed at ACE at about 11h UTC. The interplanetary magnetic field has since been moderately southwards and will likely cause the geomagnetic field to become unsettled to active. Flares and CMEs A total of 9 C class events were recorded on October 18. Region 9658 produced a C6.5/1N flare at 13:50 UTC. Region 9661 generated a C4.7 flare at 16:12 and a C3.0 flare at 23:44 UTC. Region 9672 was the source of a C8.5 flare at 19:05 UTC. Region 9661 produced an X1.6/2B flare at 01:05 UTC on October 19. A strong type II radio sweep accompanied the event. Early LASCO images indicate that a significant CME was produced. Further details will be posted later today when more images are available. The CME could impact Earth sometime between noon on October 20 and early on October 21. A proton flux enhancement has been observed but it is too early to tell if proton event levels will be reached. After the X1 flare several M flares were recorded. First an M5.8 event at 01:25, then an M1.3 event at 02:25, an M1.5 flare at 02:58 and an M1.0 flare at 03:16 UTC. The background x-ray flux is at the class C2 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on October 19 and quiet to major storm on October 20-21. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair. 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 9655 2001.10.06 S22W89 plage 9657 2001.10.08 N22W62 plage 9658 2001.10.09 15 S14W48 0180 EAO beta-gamma-delta 9659 2001.10.10 N05W88 plage 9660 2001.10.10 N13W75 plage 9661 2001.10.10 24 N16W23 0660 EKI beta-gamma-delta 9662 2001.10.11 7 N10W51 0040 DSO 9663 2001.10.11 S16W30 plage 9664 2001.10.12 N07W62 plage 9666 2001.10.14 S11W21 plage 9667 2001.10.14 2 N26E18 0040 HAX 9668 2001.10.15 N29W38 plage 9669 2001.10.15 20 N13E28 0140 EAI 9670 2001.10.16 12 S18E45 0370 FKO beta-gamma 9671 2001.10.17 8 N15E18 0030 DSO beta-gamma 9672 2001.10.18 3 S21E69 0100 HAX 9673 2001.10.18 1 N03E73 0110 HSX Total number of sunspots: 92 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2000.09 182.1 109.7 116.3 (-2.3) 2000.10 167.4 99.4 114.5 (-1.8) 2000.11 178.8 106.8 112.7 (-1.8) 2000.12 173.6 104.4 112.0 (-0.7) 2001.01 166.6 95.6 108.7 (-3.3) 2001.02 146.6 80.6 104.1 (-4.6) 2001.03 177.7 113.5 104.8 (+0.7) 2001.04 177.7 107.7 (107.7 predicted, +2.9) 2001.05 147.1 96.6 (108.1 predicted, +0.4) 2001.06 173.0 134.0 (106.3 predicted, -1.8) 2001.07 131.3 82.2 (105.1 predicted, -1.2) 2001.08 162.9 106.8 (105.7 predicted, +0.6) 2001.09 233.2 150.7 (105.1 predicted, -0.6) 2001.10 190.2 (1) 103.3 (2) (102.3 predicted, -2.8) 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]