Solar Terrestrial Activity Report [Image] Last update April 29, 2000 at 01:25 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 unsettled to active on April 28. Solar wind speed ranged between 380 and 437 km/sec under the influence of a fairly slow coronal stream. Solar flare activity was low. Solar flux was 183.4, the planetary A index was 17 (3-hour K indices: 4343 3333, Boulder K indices: 4333 2333). Region 8965 was quiet and stable, the region will rotate off the visible disk early on April 30. Region 8967 decayed slowly and could produce occasional C flares. Region 8968 rotated over the west limb. Region 8969 decayed into spotless plage. Region 8970 was quiet but did not change significantly and could still produce a major flare. Region 8971 was quiet and seems to be developing slowly, the region has a minor chance of generating an M flare. Regions 8972 and 8973 were quiet and stable, region 8973 has rotated off the visible disk. New region 8976 in the southeast quadrant was finally numbered and has developed fairly quickly, the region has reversed polarities. C class flares are possible. New region 8977 emerged near the central meridian in the southwest quadrant. New region 8978 was finally numbered as well as it developed slowly in the northeast quadrant. New region 8979 emerged in the northeast quadrant. New region 8980 rotated into view at the southeast limb. Flares and CMEs A total of 2 C flares were recorded on April 28. A prominence near region 8967 erupted and produced a C5.2/1N event at 18:51 UTC, this was accompanied by a strong type II sweep and a coronal mass ejection mainly off the northwest quadrant and the north pole. The background x-ray flux is at the class B6 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 unsettled on April 29-30. 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 7 S16W76 0020 CRO 8966 20000418 S13W65 plage 8967 20000419 4 N24W54 0090 FSO 8968 20000419 3 S11W91 0030 BXO 8969 20000420 N12W53 plage 8970 20000420 49 S13W22 1020 EKC beta-gamma 8971 20000421 24 N18W22 0780 FKO beta-gamma 8972 20000421 4 N36W85 0180 EAO 8973 20000422 2 N22W93 0030 BXO 8975 20000423 S25W15 plage 8976 20000428 11 S11E03 0040 DSO 8977 20000428 4 S14W04 0010 BXO 8978 20000428 8 N19E04 0020 BXO 8979 20000428 1 N21E47 0000 AXX 8980 20000428 1 S16E71 0000 AXX Total number of sunspots: 118 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 2000.04 185.0 (1) 184.1 (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]