Solar Terrestrial Activity Report [Image] Last update April 9, 2000 at 05:05 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update April 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2000)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to active on April 8. Solar wind speed ranged between 469 and 578 km/sec. Solar flare activity was moderate. Solar flux was 182.0, the planetary A index was 14 (3-hour K indices: 2244 3333, Boulder K indices: 2233 3333). Region 8936 decayed slowly and was quiet, isolated C class flares are possible. Region 8938 was quiet and stable. Region 8939 decayed losing all but one spot. Regions 8943, 8944 and 8945 were quiet and stable. Region 8948 developed slowly and still has magnetic delta configuration within the main penumbra. Further M class flares are likely over the next few days, a major flare could be possible as well. Region 8949 was quiet and developed slowly. Region 8951 was quiet but has a fair chance of producing a minor M class flare. Region 8952 was quiet and stable. A fairly active region will be rotating into view at the northeast limb today or tomorrow. Flares and CMEs A total of 9 C flares and 2 M flares were recorded on April 8. Region 8948 was the source of both M flares and all but one of the C flares. An M2.0/1B flare was observed at 02:40, a C8.2 flare occurred at 09:43 and an impulsive M1.8/1N flare was noted at 20:46 UTC. April 7: A sub flare in region 8944 at 08:34 UTC triggered a filament eruption over the central meridian and solar equator. This was not a large eruption but may have produced a geoeffective coronal mass ejection. If there is any impact it will likely occur on April 10 and cause the geomagnetic field to become unsettled to active. The background x-ray flux is at the class B9 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on April 9. There is a chance of a minor CME impact on April 10 and this could result in unsettled to active conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very 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 8936 20000329 5 S16W61 0070 CAO 8938 20000330 2 S10W61 0000 BXO 8939 20000330 1 N22W53 0070 HSX 8940 20000330 N15W56 plage 8943 20000331 1 N22W87 0050 HSX 8944 20000401 5 N07W21 0030 CSO 8945 20000401 2 S20W15 0010 AXX 8946 20000403 S24W75 plage 8947 20000403 N23W63 plage 8948 20000404 42 S15E14 0210 EAI beta-gamma-delta 8949 20000405 6 S19E43 0200 EAO 8951 20000407 2 N13E64 0120 DSO 8952 20000407 1 S23E36 0000 AXX Total number of sunspots: 67 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.03 126.3 69.1 83.8 (-0.8) 1999.04 117.2 63.9 85.4 (+1.6) 1999.05 148.4 106.3 90.4 (+5.0) 1999.06 169.8 137.7 93.0 (+2.6) 1999.07 165.6 113.5 94.4 (+1.4) 1999.08 170.7 93.7 97.5 (+3.1) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.4 (108.6 predicted, +6.3) 1999.11 191.5 132.7 (112.3 predicted, +3.7) 1999.12 169.8 86.4 (111.9 predicted, -0.4) 2000.01 158.1 90.2 (112.7 predicted, +0.8) 2000.02 174.1 112.3 (116.2 predicted, +3.5) 2000.03 208.2 138.2 2000.04 199.2 (1) 58.0 (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]