Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 19, 1999 at 02:40 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update October 2, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update October 2, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update October 2, 1999)] [Historical solar and geomagnetic data charts 1954-1999] [Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was quiet to unsettled on October 18. Solar wind speed ranged between 393 and 491 km/sec, generally decreasing. Solar flare activity was low. Solar flux was 172.7, the planetary A index was 6 (3-hour Kp indices: 1111 3322, Boulder K indices: 0202 3322). Region 8728 decayed further with only a couple of spots remaining. Region 8729 decayed slowly. Region 8731 decayed slowly but is still a large region capable of producing a major flare. The likelihood of a major flare is decreasing and the region has been fairly quiet over the last few days. Region 8732 was most unchanged and could produce further C class flares. Region 8734 decayed slowly and was quiet, the region could become spotless today. Region 8735 was quiet and stable, as was region 8736. Flares and CMEs 8 C flares were recorded on October 18 with regions 8728, 8731 and 8732 producing one C flare each. The remaining flares were optically uncorrelated, amongst them the largest flare of the day, a C6.6 impulisve flare at 01:14 UTC. A filament eruption in the southeast quadrant near the central meridian was first observed in EIT images at 23:12 UTC on October 17. A coronal mass ejection was observed shortly afterwards covering the south pole and the east limb. The CME could impact earth on October 21. A larger and longer lasting CME was observed off the northeast limb early on October 18 following a filament eruption centered near region 8735. This filament eruption may have been triggered by the eruption in the southeast quadrant. The background x-ray flux is at the class B6 level. Coronal holes A well placed and well defined coronal hole in the northern hemisphere will move into a geoeffective position on October 22. Forecast The geomagnetic field is expected to be quiet to unsettled on October 19-20. On October 21 a CME could reach the earth and cause unsettled to active conditions. A coronal stream will cause the geomagnetic field to reach unsettled to minor storm levels October 25-26. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally poor and improving. 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 8728 991008 2 N22W59 0170 CSO 8729 991009 1 N16W49 0000 AXX 8731 991011 35 N19W27 0980 FKC beta-gamma 8732 991012 19 N21W41 0180 FAO 8733 991012 N26W76 plage 8734 991015 1 N17W23 0000 AXX 8735 991016 6 N19E09 0030 CSO 8736 991017 1 S24E20 0000 AXX Total number of sunspots: 65 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 83.8 (-0.8) 9904 117.2 63.9 (84.9 predicted, +1.1) 9905 148.4 106.4 (89.5 predicted, +4.6) 9906 169.8 137.4 (93.6 predicted, +4.1) 9907 165.6 113.5 9908 170.7 93.7 9909 135.7 70.6 9910 160.0 (1) 93.0 (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]