Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 25, 1999 at 03:15 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 unsettled to minor storm on October 24. Solar wind speed ranged between 525 and 634 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 158.8, the planetary A index was 23 (3-hour Kp indices: 4454 4334, Boulder K indices: 3454 3323). Region 8737 decayed slowly and was quiet. Region 8738 was quiet and stable. Region 8739 was mostly unchanged and could produce minor M class flares. Region 8741 did not change significantly and has minor M class flaring potential. Region 8742 was mostly quiet but could produce an M class flare. Flares and CMEs 5 C flares were recorded on October 24. Only one of the flares was optically correlated, region 8741 produced a C2.1 impulsive flare at 16:06 UTC. The background x-ray flux is at the class B6 level. Coronal holes A well placed coronal hole in the northern hemisphere was in a geoeffective position on October 21-22. A small, isolated coronal hole in the northern hemisphere could rotate into a geoeffective position on October 26. Forecast The geomagnetic field is expected to be unsettled to active on October 25. Quiet to active is expected for October 26 and quiet to unsettled is likely October 27-28. A coronal stream could reach the earth on October 29 and cause unsettled to active intervals. 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 8735 991016 N18W71 plage 8736 991017 S25W58 plage 8737 991019 13 S13W54 0330 EKO 8738 991020 6 N18W27 0030 CSO 8739 991020 36 S12E16 0420 EKI beta-gamma 8741 991022 17 S26E36 0220 EAO 8742 991023 8 N08E68 0280 EKO Total number of sunspots: 80 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 160.4 (1) 122.4 (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]