Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 8, 1999 at 03:10 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 on October 7. Solar wind speed ranged between 357 and 473 km/sec. Solar flare activity was low. Solar flux was 129.4, the planetary A index was 6 (3-hour Kp indices: 2221 2221, Boulder K indices: 2332 0112). Region 8713 reemerged with a couple of spots. Region 8714 was quiet and stable. Region 8716 decayed slowly. Regions 8718 and 8719 were quiet and stable. Region 8720 decayed slowly. Region 8721 was quiet and stable. Region 8722 decayed slowly and was quiet. Regions 8723, 8724, 8725 and 8726 were quiet and stable. New region 8727 emerged in the northeast quadrant. None of the regions on the visible disk are particularly active, however, just behind the northeast limb, an interesting region has been quite active over the last couple of days. The region could be capable of M class flaring. Flares and CMEs A total of 4 C flares were recorded on October 7. Region 8720 produced a C2.9 flare at 04:43 UTC while region 8716 managed to generate a C2.2 flare at 05:22 UTC. The remaining 2 flares (one of them occurring just before midnight) were optically unaccounted, SOHO EIT images indicate that the region just behind the northeast limb was the source of the events. The background x-ray flux is at the class B5 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 9-13. Forecast The geomagnetic field is expected to be quiet to unsettled October 8-11. A coronal hole based disturbance is likely to start on October 12. The disturbance will likely last until at least October 16 with peaks early and late in the period. Unsettled to minor storm would be likely most days October 12-16 with a chance of isolated major storm intervals. 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 N24W67 plage 8713 990929 2 S14W45 0000 BXO 8714 990929 2 N13W36 0010 BXO 8715 990930 N12W46 plage 8716 991002 2 N21E05 0190 HSX 8718 991003 4 S28W50 0030 CSO 8719 991003 3 S22W02 0080 CSO 8720 991003 16 N13E14 0050 DAO 8721 991003 6 S19E05 0070 DSO 8722 991004 8 N14W20 0040 DRO 8723 991004 3 N20E39 0020 CSO 8724 991005 4 N18W38 0010 BXO 8725 991005 1 S25E41 0040 HSX 8726 991006 1 S21E14 0010 HSX 8727 991007 2 N18E53 0010 BXO Total number of sunspots: 54 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 133.7 (1) 29.0 (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]