Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 26, 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 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 active on October 25. Solar wind speed ranged between 517 and 608 km/sec under the influence of a coronal stream. Solar flare activity was moderate. Solar flux was 179.2, the planetary A index was 18 (3-hour Kp indices: 3344 4331, Boulder K indices: 3344 4322). Region 8737 was mostly unchanged, the region will rotate behind the west limb on October 27. Region 8738 was quiet and stable. Region 8739 developed several new spots and became significantly more complex. The region could produce a major flare at any time over the next 2-3 days. Region 8741 developed slowly and could produce another minor M flare. Region 8742 developed slowly and has M class flare potential. New region 8743 emerged in the southeast quadrant near region 8741. New region 8744 emerged in the northeast quadrant near region 8742. Flares and CMEs 8 C flares and 1 M flare were recorded on October 25. Region 8741 produced an impulsive M1.7/1B at 06:31 UTC, no obvious CME was observed. Additionally region 8741 was the source of 2 of the C flares, with regions 8737 (1 flare), 8739 (3 flares) and 8742 (1 flare) producing the remaining optically correlated flares. Region 8739 was the source of a long duration C9.8 event which peaked at 23:50 UTC. A large part of the southern polar crown filament erupted resulting in a partial halo coronal mass ejection over most of the southern hemisphere, the CME was first visible in LASCO C2 at 14:26 UTC. There is a slight chance the CME could impact the earth on October 28. The background x-ray flux is at the class C1 level. Coronal holes 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 quiet to active on October 26. 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 poor to 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 Location region numbered no. at Area Classification Comment sunspots midnight 8735 991016 N18W84 plage 8736 991017 S25W71 plage 8737 991019 5 S13W67 0370 EAO 8738 991020 4 N18W40 0020 CRO 8739 991020 55 S12E03 0570 EHI beta-gamma-delta 8741 991022 18 S25E22 0280 EAO 8742 991023 19 N08E54 0450 EKO 8743 991025 4 S15E20 0010 BXO 8744 991025 4 N08E43 0010 BXO Total number of sunspots: 99 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 161.2 (1) 127.9 (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]