Solar Terrestrial Activity Report [Image] Last update April 12, 2000 at 03:25 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update 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 1954-2000 (last update April 12, 2000)] Recent development The geomagnetic field was quiet to active on April 11. Solar wind speed ranged between 355 and 446 km/sec. Solar flare activity was moderate. Solar flux was 181.5, the planetary A index was 10 (3-hour K indices: 3342 3122, Boulder K indices: 2331 3321). Region 8948 decayed slowly and simplified, further minor M class flares are possible. Region 8949 was quiet and stable, as were regions 8951 and 8953. Region 8954 developed slowly and was mostly quiet. Region 8955 was mostly quiet but should be capable of at least C class flaring. Region 8956 was quiet and stable. Region 8957 decayed and was quiet. New region 8958 rotated partly into view at the northeast limb. Flares and CMEs A total of 8 C flares and 2 M flares were recorded on April 11. Region 8948 produced a C1.7 flare at 03:02, a C1.3 flare at 07:10, a C2.2 flare at 07:51, an M1.0/1N flare at 18:10 and an M1.1 flare at 23:37 UTC. Region 8939 produced a C1.3 flare at 01:43 UTC while at the west limb. April 9: Region 8948 produced an M3.1/2B flare at 23:42 UTC. The event was accompanied by a moderately strong type II sweep and occurred right over the central meridian. A slow moving full halo CME was observed in LASCO images. The CME has a fairly high probability of impacting Earth on April 13 but will probably not cause a significant disturbance, unsettled to active is most likely. The background x-ray flux is at the class B8 level. Coronal holes A small and well placed coronal hole near the equator will rotate into a geoeffective position on April 12. Forecast The geomagnetic field is expected to be quiet to unsettled on April 12. A CME will likely impact Earth on April 13 causing unsettled to active conditions. A weak coronal stream could start on April 15 and will likely result in unsettled to active intervals. 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 8944 20000401 N08W61 plage 8945 20000401 S23W55 plage 8948 20000404 21 S15W25 0110 EAI beta-gamma 8949 20000405 9 S19W05 0100 CSO 8951 20000407 3 N11E24 0100 CSO 8952 20000407 S23W04 plage 8953 20000409 7 S17E41 0070 DSO 8954 20000410 5 N30E53 0020 CAO 8955 20000410 6 S22E71 0220 ESO 8956 20000410 1 N11E40 0000 AXX 8957 20000410 3 S12W27 0000 AXX 8958 20000411 3 N17E66 0010 BXO Total number of sunspots: 58 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 2000.04 193.5 (1) 74.1 (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]