Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update September 28, 1999 at 02:35 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update September 1, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 1, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 1, 1999)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was active to minor storm on September 27. Solar wind speed ranged between 558 and 703 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 123.8, the planetary A index was 37 (3-hour Kp indices: 4455 5544, Boulder K indices: 5454 5433). Region 8704 was mostly unchanged and will rotate over the west limb on September 29. Region 8706 was quiet and stable. Region 8708 was quiet and stable, the region appears to be spotless early on September 28. Region 8710 was quiet and stable. An active region near the southeast limb should rotate into view within a couple of days. Flares and CMEs Region 8704 generated the only flare on September 27, a C2.1 event at 09:12 UTC. The background x-ray flux is at the class B3 level. Coronal holes A coronal hole in the southern hemisphere will rotate into a geoeffective position on October 1-3. Forecast The geomagnetic field is expected to be quiet to active on September 28 with a chance of isolated minor storm intervals. Quiet to unsettled is expected for September 29-30. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally very 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 8704 990917 1 S19W67 0100 HSX 8705 990918 S11W89 plage 8706 990919 3 N21W27 0080 CAO 8707 990922 S07W73 8708 990922 4 S11W09 0000 BXO 8709 990924 S15E09 plage 8710 990926 1 N19E64 0040 HSX Total number of sunspots: 9 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 9807 114.0 66.6 65.5 (+3.0) 9808 136.0 92.2 67.8 (+2.3) 9809 138.3 92.9 69.5 (+1.7) 9810 117.2 55.5 70.5 (+1.0) 9811 140.1 74.0 73.0 (+2.5) 9812 150.1 81.9 77.9 (+4.9) 9901 140.6 62.0 82.6 (+4.7) 9902 141.9 66.3 84.6 (+2.0) 9903 126.3 68.8 (83.9 predicted, -0.7) 9904 117.2 63.9 (85.0 predicted, +1.2) 9905 148.4 106.4 (89.4 predicted, +4.4) 9906 169.8 137.4 9907 165.6 113.5 9908 170.7 93.7 9909 136.8 (1) 100.0 (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]