Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 10, 1999 at 04:35 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 9. Solar wind speed ranged between 381 and 452 km/sec. Solar wind speed increased slowly from 13h UTC until midnight, and quickly from midnight until 02h UTC on October 10. This quick increase was accompanied by a significant strengthening of the interplanetary magnetic field. A moderately strongly southward swing of the IMF was observed after 03h UTC. The disturbance is highly likely related to an undetected coronal mass ejection. Solar flare activity was low. Solar flux was 152.8, the planetary A index was 6 (3-hour Kp indices: 0121 2233, Boulder K indices: 1121 2212). Region 8713 reemerged with a couple of spots, the region will rotate off the visible disk on October 11. Region 8714 was quiet and stable, as were regions 8716, 8718 and 8719. Region 8718 appears to be spotless early on October 10. Region 8720 decayed slowly and is unlikely to produce other than occasional C flares. Region 8721 was quiet and stable. Region 8722 decayed further and appears to be spotless early on October 10. Regions 8723, 8724, 8725, 8726 and 8727 were quiet and stable. Region 8728 rotated fully into view and should be capable of C class flaring. New region 8729, to the southeast of region 8728, rotated partly into view at the northeast limb. The region could be capable of M class flaring. Flares and CMEs Only 2 C flares were recorded on October 9. Region 8720 produced a C2.0 flare at 12:54 UTC while a C2.2 flare at 04:34 was optically unaccounted. The background x-ray flux is at the class B6 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 minor storm on October 10 with a possibility of major storm intervals. A coronal hole based disturbance is likely to start on October 12. The disturbance could last until at least October 16 with peaks early and late in the period. Unsettled to minor storm will 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 8713 990929 3 S12W70 0010 BXO 8714 990929 1 N18W56 0000 AXX 8715 990930 N12W72 plage 8716 991002 11 N22W20 0170 CAO 8718 991003 2 S26W81 0020 AXX 8719 991003 2 S22W32 0070 HSX 8720 991003 20 N14W11 0030 BXO 8721 991003 7 S17W24 0030 CSO 8722 991004 1 N15W44 0000 AXX 8723 991004 7 N20E14 0010 BXO 8724 991005 3 N22W62 0000 BXO 8725 991005 2 S25E14 0040 HSX 8726 991006 5 S19W18 0010 BXO 8727 991007 3 N18E25 0010 HSX 8728 991008 10 N21E62 0150 CAO 8729 991009 8 N11E67 0040 CRO Total number of sunspots: 85 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 137.8 (1) 41.7 (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]