Solar Terrestrial Activity Report [Image] Last update May 3, 2000 at 03:55 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 active on May 2. Solar wind speed ranged between 429 and 897 km/sec. A solar wind shock was observed at ACE near 09:10 UTC. By 11h UTC solar wind speed had increased to rarely observed 900 km/sec. The interplanetary magnetic field did not strengthen considerably and was mostly northerly after 10:30 UTC. Solar wind density remained at a very low level. The source of the disturbance is probably the eruption in region 8976 on April 30. Solar flare activity was moderate. Solar flux was 152.8, the planetary A index was 18 (3-hour K indices: 3234 4334, Boulder K indices: 3224 4323). Region 8970 decayed further but could still produce a minor M flare before departing the visible disk late today. Region 8971 decayed slowly and could produce another M flare before rotating out of view early on May 4. Regions 8976, 8977, 8978, 8980 and 8981 were quiet and stable. A couple of active regions will be rotating into view at the northeast limb today and an active region at the southeast limb will become visible within a couple of days. Flares and CMEs A total of 3 C flares and 1 M flare were recorded on May 2. Region 8971 produced an M2.8 flare/1N impulsive flare at 14:51 UTC and a C2.0/1F flare at 07:17 UTC. Region 8970 was the source of a C2.0 flare at 16:43 UTC. A filament eruption was in progress at 21:11 UTC in the northwest hemisphere at approximately position N25W15. The background x-ray flux is at the class B4 level. Coronal holes A small coronal hole in the northern hemisphere was likely in a geoeffective position on April 30. A coronal hole in the southern hemisphere was likely in a geoeffective position on May 1-2. Forecast The geomagnetic field is expected to be quiet to active on May 3-4. Coronal streams could cause unsettled to active intervals on May 3 and 4. 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 8970 20000420 6 S13W78 0350 DAO beta-gamma 8971 20000421 9 N19W74 0640 EKO beta-gamma 8975 20000423 S25W67 plage 8976 20000428 5 S12W49 0040 CSO 8977 20000428 5 S13W61 0010 BXO 8978 20000428 7 N20W46 0170 CSO 8979 20000428 N21W05 plage 8980 20000428 1 S16E18 0020 HSX 8981 20000501 5 S23E17 0030 CRO Total number of sunspots: 38 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 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) 1999.10 164.8 116.4 107.7 (+5.4) 1999.11 191.5 132.7 (110.3 predicted, +2.6) 1999.12 169.8 86.4 (109.0 predicted, -1.3) 2000.01 158.1 90.2 (109.4 predicted, +0.4) 2000.02 174.1 112.3 (112.9 predicted, +3.5) 2000.03 208.2 138.2 (116.6 predicted, +3.7) 2000.04 184.2 125.3 2000.05 155.3 (1) 7.4 (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]