Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 6, 1999 at 01:45 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 unsettled to active on October 5. Solar wind speed ranged between 432 and 588 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 146.2, the planetary A index is estimated at 16 (3-hour Kp indices: 3333 4334, Boulder K indices: 3232 3424). Region 8710 decayed into spotless plage, as did region 8713. Region 8714 was quiet and stable. Region 8715 reemerged with a couple of spots but appears to be spotless again early on October 6. Region 8716 was mostly quiet and stable. Region 8718 developed slowly and could become capable of C class flaring. Region 8719 was quiet and stable. Region 8720 could produce further C class flares. Region 8721 was quiet and stable. Region 8722 developed further and could produce C flares. Region 8723 was quiet and stable. New region 8724 emerged in the northwest quadrant. New region 8725 rotated into view at the southeast limb. Flares and CMEs There were only 2 C flares on October 5. Region 8720 produced a C2.8 flare at 05:51 UTC while a C1 flare earlier in the day was optically unaccounted. The background x-ray flux is at the class B4 level. Coronal holes A weak coronal hole in the southern hemisphere could rotate into a geoeffective position from October 10. Forecast The geomagnetic field is expected to be quiet to unsettled October 6-9. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally fair to 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 8710 990926 N24W41 plage 8712 990929 S11W74 plage 8713 990929 S16W25 plage 8714 990929 2 N14W09 0010 BXO 8715 990930 2 N12W20 0000 BXO 8716 991002 5 N20E32 0230 CSO 8717 991003 S26W85 plage 8718 991003 7 S27W21 0040 DSO 8719 991003 8 S22E26 0100 DSO beta-gamma 8720 991003 4 N13E42 0060 CSO 8721 991003 7 S18E34 0110 EAO 8722 991004 11 N14E08 0050 DAO 8723 991004 1 N20E67 0040 HAX 8724 991005 2 N19W11 0010 CSO 8725 991005 1 S24E67 0050 HAX Total number of sunspots: 50 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 134.6 (1) 17.4 (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]