Solar Terrestrial Activity Report [Image] Last update May 2, 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 1. Solar wind speed ranged between 415 and 668 km/sec. A coronal stream arrived just after 14h UTC and caused solar wind speed to increase significantly. Solar flare activity was moderate. Solar flux was 157.7, the planetary A index was 14 (3-hour K indices: 2442 3333, Boulder K indices: 2331 3442). Region 8970 decayed slowly. The region could produce occasional C flares and has M class flaring potential. Region 8971 developed slowly and could produce further M class flares. Region 8976 decayed slowly and was quiet. Region 8977 was quiet and stable, as were regions 8978 and 8980. New region 8981 emerged in the southeast quadrant near region 8981. Flares and CMEs A total of 3 C flares and 1 M flare were recorded on May 1. Region 8971 produced an M1.1 flare at 10:27 UTC. April 30: Region 8976 was the source of a C7.7/1N long duration event peaking at 08:08 UTC. This event was accompanied by a moderately strong type II sweep and a partial halo coronal mass ejection covering most of the southern hemisphere. There is a fair chance of a terrestrial impact on May 3. April 29: 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 B4-B5 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 will likely rotate into a geoeffective position on May 1-2. Forecast The geomagnetic field is expected to be quiet to active on May 2-4. CME effects could be observed on May 2 and 3 causing unsettled to active intervals, perhaps with isolated minor storm intervals. 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 15 S13W64 0550 DKO beta-gamma 8971 20000421 9 N20W61 0860 EKO beta-gamma 8975 20000423 S25W54 plage 8976 20000428 7 S12W37 0040 CSO 8977 20000428 7 S13W47 0020 CSO 8978 20000428 7 N20W33 0030 CSO 8979 20000428 N21E08 plage 8980 20000428 1 S16E31 0010 HSX 8981 20000501 5 S23E30 0020 CSO Total number of sunspots: 51 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) 1999.10 164.8 116.4 107.7 (+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 2000.05 157.7 (1) 3.9 (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]