Solar Terrestrial Activity Report [Image] Last update May 22, 2000 at 04:05 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update May 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update May 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update April 12, 2000)] Recent development The geomagnetic field was quiet to unsettled on May 21. Solar wind speed ranged between 380 and 482 km/sec. Solar flare activity was low. Solar flux was 232.3, the planetary A index was 7 (3-hour K indices: 2322 2222, Boulder K indices: 2332 1211). Region 8996 was mostly unchanged and will likely continue to produce C flares. The potential for a major flare still exists. Region 8998 developed a magnetic delta configuration and could produce isolated M flares. Region 8999 was mostly quiet and stable. Region 9002 added a few more spots and remains capable of producing a major flare. Region 9004 was generally unchanged and could produce occasional M flares. Region 9009 was quiet and stable. Region 9010 developed slowly and could produce C flares. Region 9011 was mostly quiet and stable. Region 9012 decayed slowly and could become spotless today. Regions 9013 and 9014 both decayed into spotless plage. Flares and CMEs A total of 7 C flares were observed on May 21. Region 9011 produced a C3.7 flare 00:12 UTC. Region 8998 generated a C2.5 flare at 06:34 UTC. Region 8996 was the source of a C8.2 flare at 10:23 and a C2.1 flare at 19:43 UTC. Region 9004 produced a C1.9 flare at 16:44 UTC. May 20: Region 8998 produced an interesting C7.6/1N flare at 05:35 UTC. This event was accompanied by strong type II sweeps and a moderately strong type IV sweep. A partial halo coronal mass ejection was observed covering the southeast limb, the south pole, the southwest limb as well as part of the northwest limb. There is a fair chance of a terrestrial impact from this CME on May 23. The background x-ray flux is at the class C1 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on May 22. A CME could impact Earth on May 23 causing unsettled to minor storm conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to 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 8992 20000509 N10W83 plage 8996 20000511 39 S21W49 0810 EKC 8997 20000511 S17W58 plage 8998 20000512 37 S12W33 0440 EAC beta-gamma-delta 8999 20000513 9 N20W36 0030 CRO 9002 20000514 58 N19W10 0730 FKI 9004 20000515 13 N12W21 0530 DKC beta-delta 9007 20000517 S42W40 plage 9008 20000517 S30W01 plage 9009 20000518 5 S15E29 0040 CSO 9010 20000518 17 N21E30 0110 CAO 9011 20000519 2 N17E40 0250 HKX 9012 20000519 1 S29W50 0000 AXX 9013 20000520 S06W74 plage 9014 20000520 S43E08 plage Total number of sunspots: 181 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.04 117.2 63.9 85.5 (+1.7) 1999.05 148.4 106.3 90.5 (+5.0) 1999.06 169.8 137.7 93.1 (+2.6) 1999.07 165.6 113.5 94.5 (+1.4) 1999.08 170.7 93.7 97.4 (+2.9) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.7 (+5.4) 1999.11 191.5 133.2 (110.4 predicted, +2.7) 1999.12 169.8 84.6 (110.2 predicted, -0.2) 2000.01 158.1 90.2 (111.5 predicted, +1.3) 2000.02 174.1 112.3 (114.9 predicted, +3.4) 2000.03 208.2 138.2 (118.7 predicted, +3.8) 2000.04 184.2 125.3 2000.05 191.1 (1) 136.8 (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]