Solar Terrestrial Activity Report [Image] Last update April 30, 2000 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 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 unsettled on April 29. Solar wind speed ranged between 380 and 448 km/sec under the influence of a fairly slow coronal stream. Solar flare activity was low. Solar flux was 174.9, the planetary A index was 12 (3-hour K indices: 3322 3333, Boulder K indices: 3322 2233). Region 8965 was quiet and stable, the region has rotated off the visible disk. Region 8967 decayed slowly and was quiet, the region is rotating over the west limb. Region 8970 decayed significantly and will likely continue to produce minor C flares. A major flare is possible but the likelihood of such an event is decreasing. Region 8971 decayed slowly and was quiet. The region has a minor chance of generating an M flare. Region 8972 rotated off the visible disk. Region 8976 was mostly unchanged and could produce further C flares. Region 8977 was quiet and stable, as was region 8978. Region 8979 decayed into spotless plage. Region 8980 was quiet and stable. Flares and CMEs A total of 5 C flares were recorded on April 29. Region 8970 produced a C2.0 flare at 05:28 and a C1.0 flare at 13:43 UTC. Region 8976 was the source of a long duration C3.0 event peaking at 12:06 UTC. A filament over the central meridian and solar equator erupted starting at 11:12 UTC. This event may have produced a geoeffective CME and could start a disturbance on May 2. The background x-ray flux is at the class B5 level. Coronal holes Small coronal holes in the northern hemisphere could rotate into geoeffective positions on April 29-30, however, they seem to have closed over the last day and will likely not contribute to any geomagnetic disturbance. Forecast The geomagnetic field is expected to be quiet to active on April 30 and quiet to unsettled on May 1. 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 8965 20000417 1 S15W89 0000 AXX 8966 20000418 S13W78 plage 8967 20000419 2 N23W77 0060 HSX 8969 20000420 N12W66 plage 8970 20000420 29 S15W36 0780 EKC beta-gamma 8971 20000421 9 N18W36 0670 EKO beta-gamma 8975 20000423 S25W28 plage 8976 20000428 9 S11W14 0060 DAO 8977 20000428 5 S13W20 0010 BXO 8978 20000428 6 N19W10 0040 CSO 8979 20000428 N21E34 plage 8980 20000428 1 S16E58 0010 HSX Total number of sunspots: 62 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 2000.04 184.7 (1) 188.8 (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]