Solar Terrestrial Activity Report [Image] Last update April 13, 2000 at 02:50 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 12. Solar wind speed ranged between 332 and 403 km/sec. Solar flare activity was moderate. Solar flux was 173.0, the planetary A index was 5 (3-hour K indices: 3222 2122, Boulder K indices: 3222 2122). Region 8948 was mostly unchanged and could produce further minor M class flares. Region 8949 was quiet and stable, as were regions 8951, 8953 and 8954. Region 8955 was quiet and has minor M class flaring potential. Region 8956 developed slowly and was quiet. Region 8957 decayed into spotless plage. Region 8958 was quiet and stable. New region 8959 emerged quickly in the southeast quadrant. Flares and CMEs A total of 5 C flares and 1 M flare were recorded on April 12. Region 8948 produced an M1.3 flare at 03:35, a C1.6 flare at 09:23, a C2.4 flare at 18:58 and a C2.1 flare at 06:30 UTC. The latter flare was accompanied by a weak type II sweep, no obvious CME was observed in LASCO images. 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 fair 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 B5 level. Coronal holes A small and well placed coronal hole near the equator was in a geoeffective position on April 12. Forecast The geomagnetic field is expected to be quiet to unsettled on April 13-14, perhaps with a few active intervals. 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 N08W74 plage 8945 20000401 S23W68 plage 8948 20000404 21 S16W37 0140 DAI beta-gamma 8949 20000405 6 S19W14 0110 CSO 8951 20000407 3 N11E11 0090 CSO 8952 20000407 S23W17 plage 8953 20000409 16 S16E31 0080 DSO 8954 20000410 7 N31E40 0030 CRO 8955 20000410 9 S22E57 0260 ESO beta-gamma 8956 20000410 5 N14E24 0020 CRO 8957 20000410 S12W40 plage 8958 20000411 5 N17E53 0020 CAO 8959 20000412 10 S19E29 0070 DAO Total number of sunspots: 82 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 2000.04 191.8 (1) 79.8 (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]