Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 24, 1999 at 04:05 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 23. Solar wind speed ranged between 555 and 703 km/sec. Solar wind data towards the end of the day indicate a coronal stream has become the dominant part of the solar wid. Solar flare activity was low. Solar flux was 164.5, the planetary A index was 26 (3-hour Kp indices: 3443 5543, Boulder K indices: 2442 4433). Region 8731 rotated off the visible disk. Region 8734 decayed into spotless plage. Region 8737 decayed slowly and was quiet. Region 8738 was quiet and stable. Region 8739 developed further and could produce minor M class flares. Region 8740 rotated off the visible disk. Region 8741 developed slowly and has minor M class flaring potential. New region 8742 rotated into view at the northeast limb at a low latitude. The region has a large leader spot and appears to be capable of minor M class flaring. Flares and CMEs 9 C flares were recorded on October 23. Region 8741 produced 4 C flares while the remaining flares were optically unaccounted. LASCO EIT images indicate that the regions which have just rotated behind the northwest limb were the source of most of these events, among them a C2.7 long duration event at 01:07 UTC associated with a moderately strong type II sweep and a wide coronal mass ejection. The background x-ray flux is at the class B7 level. Coronal holes A well placed coronal hole in the northern hemisphere was in a geoeffective position on October 21-22. Forecast The geomagnetic field is expected to be unsettled to active on October 24-26 with a chance of isolated minor storm 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 8734 991015 N16W85 plage 8735 991016 N18W58 plage 8736 991017 S25W45 plage 8737 991019 17 S14W40 0270 EKO 8738 991020 6 N17W13 0020 CSO 8739 991020 23 S12E30 0440 EKI beta-gamma 8741 991022 17 S25E50 0210 EAO beta-gamma 8742 991023 1 N06E82 0250 HKX Total number of sunspots: 73 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 160.5 (1) 118.2 (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]