Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 18, 1999 at 03:00 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 minor storm on October 17. Solar wind speed ranged between 470 and 594 km/sec, generally decreasing. Solar flare activity was low. Solar flux was 178.0, the planetary A index was 26 (3-hour Kp indices: 4355 5312, Boulder K indices: 3345 5421). Region 8728 decayed significantly losing most of its spots. Region 8729 decayed slowly and was quiet. Region 8731 developed slowly and is a complex, large region capable of producing a major flare. Region 8732 was quiet and stable. Region 8734 decayed slowly and was quiet. Region 8735 developed slowly and could be capable of C class flaring. New region 8736 emerged in the southeast quadrant. Flares and CMEs 9 C flares were recorded on October 17, only one was optically assigned to region 8731. Flare intensity has increased early on October 18 with a C7 impulsive flare and 3 other C flares already recorded. October 15: A large scale dimming just to the south of (and over) the large group consisting of regions 8728, 8729, 8731 and 8732 was observed starting early in the day and peaking between 06:30 and 08h UTC. This may have been a slow moving coronal mass ejection, however, no obvious CME was seen in LASCO C2 movies. If there was a CME it could impact earth on October 18 or 19. The background x-ray flux is at the class B6 level. Coronal holes A small, well placed 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 18-19. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally poor to very poor but is likely to improve over the next days. 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 8727 991007 N20W78 plage 8728 991008 10 N23W40 0220 EAO 8729 991009 3 N13W41 0010 BXO 8730 991010 S11W85 plage 8731 991011 54 N13W19 1220 FKC beta-gamma-delta 8732 991012 23 N21W25 0220 EAO 8733 991012 N26W63 plage 8734 991015 2 N17W09 0010 HSX 8735 991016 6 N18E22 0040 DSO 8736 991017 1 S20E35 0010 HRX 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 159.2 (1) 88.6 (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]