Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update September 29, 1999 at 03:25 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 unsettled to active on September 28. Solar wind speed ranged between 525 and 656 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 126.0, the planetary A index was 20 (3-hour Kp indices: 4444 4334, Boulder K indices: 4444 3323). Region 8704 was quiet and stable and will rotate over the west limb today. Region 8706 was quiet and stable. Region 8708 decayed into spotless plage. Region 8710 was quiet and stable. New region 8711 emerged in the northwest quadrant. A new region is emerging in the southeast quadrant near the central meridian. An active region near the southeast limb should rotate into view within a couple of days. Flares and CMEs There were 2 optically unaccounted C flares on September 28 with the region near the southeast limb the likely source of the events. The most energetic event was a long duration C4.3 event peaking at 15:39 UTC. 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. Forecast The geomagnetic field is expected to be quiet to active on September 29. Quiet to unsettled is expected for September 30-October 2. 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 S19W81 0050 HSX 8706 990919 2 N20W41 0070 HSX 8707 990922 S07W86 plage 8708 990922 S11W22 plage 8709 990924 S15W04 plage 8710 990926 3 N19E51 0030 CSO 8711 990928 6 N23W31 0010 BXO Total number of sunspots: 12 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 (83.9 predicted, -0.7) 9904 117.2 63.9 (85.0 predicted, +1.2) 9905 148.4 106.4 (89.4 predicted, +4.4) 9906 169.8 137.4 9907 165.6 113.5 9908 170.7 93.7 9909 136.4 (1) 101.7 (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]