Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 7, 1999 at 01:30 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 quiet to unsettled on October 6. Solar wind speed ranged between 451 and 567 km/sec, generally decreasing. Solar flare activity was low. Solar flux was 133.6, the planetary A index was 6 (3-hour Kp indices: 1133 2221, Boulder K indices: 1133 2212). Region 8714 was quiet and stable. Region 8715 once again decayed into spotless plage. Region 8716 was quiet and stable, as were regions 8718 and 8719. Region 8720 developed slowly and is likely to produce further C class flares. Region 8721 decayed slowly and is unlikely to produce other than occasional C class flares. Region 8722 was mostly unchanged and remains capable of C class flaring. Regions 8723, 8724 and 8725 were quiet and stable. New region 8726 emerged in the southeast quadrant. Flares and CMEs A total of 4 small C flares were recorded on October 6. Region 8721 produced one of the events while region 8720 managed to generate 3 C flares, the largest a C2.3 flare at 13:08 UTC. The background x-ray flux is at the class B4 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, will rotate into a geoeffective position October 10-14. Forecast The geomagnetic field is expected to be quiet to unsettled October 7-9. A coronal hole based disturbance is likely to start on October 13 and last for at least 4 days. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally fair. 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 N24W54 plage 8712 990929 S11W87 plage 8713 990929 S16W38 plage 8714 990929 2 N14W22 0010 BXO 8715 990930 N12W33 plage 8716 991002 9 N21E17 0200 CSO 8718 991003 5 S27W36 0040 DAO 8719 991003 5 S22E12 0090 CSO 8720 991003 15 N13E28 0070 DSO 8721 991003 7 S19E20 0060 DAO 8722 991004 16 N14W06 0060 DAO 8723 991004 1 N19E51 0020 HSX 8724 991005 4 N19W24 0010 BXO 8725 991005 1 S24E53 0060 HSX 8726 991006 1 S20E28 0010 HSX Total number of sunspots: 66 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 134.4 (1) 23.1 (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]