Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 2, 1999 at 02:05 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] Recent development The geomagnetic field was quiet to unsettled on October 1. Solar wind speed ranged between 440 and 506, generally slowly decreasing throughout the day. Solar flare activity was low. Solar flux was 121.6, the planetary A index was 11 (3-hour Kp indices: 2323 3331, Boulder K indices: 3323 2221). Region 8706 was quiet and stable and will rotate over the west limb today. Regions 8710, 8711, 8712, 8713 and 8714 were quiet and stable, region 8712 appears to be spotless early on October 2. Region 8715 decayed into spotless plage. An active region at the northeast limb should rotate into view over the next day. Flares and CMEs Flare frequency increased sharply on October 2 with a total of 13 C flares recorded. All were optically unaccounted except a C3.6 flare at 08:13 UTC which was associated with a bright surge at the southeast limb and a moderately strong type II sweep. Most of the remaining flare are likely to have been produced by a region at the northeast limb. The background x-ray flux is at the class B5 level. Coronal holes A coronal hole in the southern hemisphere will be in a geoeffective position on October 1-3. A coronal hole in the northern hemisphere was in a possible geoeffective position on September 30-October 1. Forecast The geomagnetic field is expected to be quiet to unsettled on October 2. On October 3-6 coronal streams will likely influence the geomagnetic field resulting in unsettled to minor storm conditions. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally 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 8706 990919 1 N21W79 0020 HSX 8708 990922 S11W61 plage 8709 990924 S15W43 plage 8710 990926 1 N21E13 0010 HSX 8711 990928 1 N22W71 0000 AXX 8712 990929 1 S11W35 0000 AXX 8713 990929 1 S13E34 0010 HSX 8714 990929 2 N13E44 0020 CSO 8715 990930 N11E29 plage Total number of sunspots: 7 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 121.6 (1) 2.2 (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]