Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 13, 1999 at 02:00 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] [NEW! Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was active to major storm on October 12. Solar wind speed ranged between 536 and 654 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 184, the planetary A index is estimated at 35 (3-hour Kp indices: 4546 5444, Boulder K indices: 5535 3333). Region 8714 rotated off the visible disk. Regions 8716 and 8719 were quiet and decayed slowly. Region 8720 was quiet, the region is spotless early on October 13. Region 8721 was quiet and stable and appears to be spotless early on October 13. Regions 8725 and 8727 were quiet and stable. Region 8728 lost a few spots and seems to be slowly decaying. The region still has M class flaring potential. Region 8729 developed slowly and could soon become capable of M class flaring. Region 8731 is developing and has M class flaring potential. New region 8732 emerged near regions 8728, 8729 and 8731. New region 8733 emerged in the northeast quadrant near the central meridian. An active region is approaching the southeast limb. Flares and CMEs A total of 3 C flares were noted on October 12. Region 8731 produced a C1.8 long duration event peaking at 08:54 UTC. An optically uncorrelated C2.9 long duration event peaked at 13:37 UTC, it was accompanied by a weak type II sweep and a coronal mass ejection off the east limb. Its source could be the region just behind the southeast limb. The background x-ray flux is at the class B7 level. Coronal holes A large coronal hole mainly in the southern hemisphere but stretching across the equator and into the northern hemisphere in the eastern parts, was in a geoeffective position October 9-13. Forecast The geomagnetic field is expected to be unsettled to minor storm on October 13. Unsettled to major storm is likely on October 14-16 as the most well defined and well placed part of a large coronal hole will have been in a geoeffective position 3 days earlier. 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 8714 990929 1 N15W98 0000 AXX 8716 991002 4 N23W62 0150 CSO 8719 991003 1 S20W70 0060 HSX 8720 991003 2 N12W50 0010 AXX 8721 991003 1 S15W64 0000 AXX 8722 991004 N15W83 plage 8723 991004 N20W25 plage 8725 991005 1 S24W27 0030 HSX 8726 991006 S19W57 plage 8727 991007 4 N19W10 0030 DSO 8728 991008 19 N22E25 0560 EKI 8729 991009 16 N12E30 0090 FAO 8730 991010 S11W20 plage 8731 991011 14 N11E51 0340 EKO 8732 991012 5 N20E43 0030 BXO 8733 991012 3 N25E00 0010 BXO Total number of sunspots: 71 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 (84.5 predicted, +0.7) 9905 148.4 106.4 (88.7 predicted, +4.2) 9906 169.8 137.4 (92.8 predicted, +4.1) 9907 165.6 113.5 9908 170.7 93.7 9909 135.7 70.6 9910 145.9 (1) 59.5 (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]