Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 17, 1999 at 03:40 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 unsettled to active on October 16. Solar wind speed ranged between 578 and 738 km/sec, generally decreasing. Solar flare activity was low. Solar flux was 189.0, the planetary A index was 21 (3-hour Kp indices: 4433 4433, Boulder K indices: 4533 4423). Region 8727 decayed into spotless plage. Region 8728 became more active and produced a few C flares. Further C class flaring is likely and the region could generate a minor M flare. 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 developed slowly and was quiet. Region 8734 decayed slowly and could become spotless today or tomorrow. New region 8735 emerged quickly in the northeast quadrant. Flares and CMEs 6 C flares were recorded on October 16. Region 8728 produced the most significant event of the day, a C3.7 flare at 11:01 UTC. 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. October 14: Region 8731 produced an impulsive X1.8/1N major flare at 09:00 UTC. A moderately strong type II sweep and a strong type IV sweep accompanied the flare. A coronal mass ejection was observed at 09:26 by LASCO C2 off the east limb, later on an almost full halo CME was evident in LASCO C3 with material observed from the north pole, all around the east limb and off a large part of the southwest limb. Earth could receive a non-direct impact from this CME on October 16 or 17 causing the geomagnetic field activity level to reach active to major storm. The background x-ray flux is at the class C1 level. Coronal holes A small, well placed coronal hole in the northern hemisphere will move into a geoeffective position on October 21 or 22. Forecast The geomagnetic field is expected to be quiet to active on October 17 as the coronal stream weakens. There is a possibility of a CME impact today, should that happen active to major storm would be likely. 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 8723 991004 N20W77 plage 8725 991005 S23W79 plage 8727 991007 N20W65 plage 8728 991008 29 N23W26 0290 EAO 8729 991009 9 N13W25 0020 BXO 8730 991010 S11W72 plage 8731 991011 62 N12W03 1000 FKC beta-gamma-delta 8732 991012 19 N20W12 0210 EAO 8733 991012 N26W50 plage 8734 991015 1 N17E08 0000 AXX 8735 991016 9 N18E40 0010 BXO Total number of sunspots: 129 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 158.1 (1) 83.2 (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]