Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update September 30, 1999 at 04:20 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update September 1, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 1, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 1, 1999)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to minor storm on September 29. Solar wind speed ranged between 497 and 595 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 124.8, the planetary A index was 19 (3-hour Kp indices: 4345 3233, Boulder K indices: 4454 3313). Region 8704 rotated off the visible disk. Region 8706 was quiet and stable. Region 8710 was mostly quiet and stable. Region 8711 was quiet and stable. New region 8712 emerged in the southern hemisphere near the central meridian. New region 8713 rotated into view at the southeast limb. New region 8714 rotated into view at the northeast limb. Further small, active regions could rotate into view at the northeast limb over the next few days. Flares and CMEs A single optically unaccounted C2 flare was the only flare on September 29. The background x-ray flux is at the class B3 level. Coronal holes A coronal hole in the southern hemisphere will rotate into a geoeffective position on October 1-3. A coronal hole in the northern hemisphere is near the central meridian but is likely too far to the north to be geoeffective. Forecast The geomagnetic field is expected to be quiet to active on September 30, possibly with isolated minor storm intervals. Quiet to unsettled is expected for October 1-3. On October 4-6 a coronal stream 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 to very 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 8704 990917 1 S19W90 0030 HSX 8706 990919 1 N20W53 0060 HSX 8708 990922 S11W35 plage 8709 990924 S15W17 plage 8710 990926 1 N19E38 0020 HSX 8711 990928 4 N22W45 0020 CSO 8712 990929 4 S13W06 0010 BXO 8713 990929 2 S13E62 0000 AXX 8714 990929 1 N11E72 0000 AXX Total number of sunspots: 14 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