Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 20, 1999 at 03:45 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] [Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was mostly quiet on October 19 with a single slightly active interval 06-09 UTC. Solar wind speed ranged between 356 and 398 km/sec. Solar flare activity was low. Solar flux was 169.6, the planetary A index was 7 (3-hour Kp indices: 2241 1221, Boulder K indices: 2232 2221). Region 8728 was quiet and stable. Region 8729 decayed into spotless plage. Region 8731 lost quite a bit of its areal coverage but developed many new spots. The region could still produce a major flare. Region 8732 developed several new spots and a weak magnetic delta configuration. The region could produce a minor M flare. Region 8734 decayed into spotless plage. Region 8735 was quiet and stable, as was region 8736. New region 8737 in the southeast quadrant near region 8736 developed very quickly. Should it continue to develop at the current rate the region will soon become capable of minor M class flaring. An active region at the southeast limb should rotate into view today or tomorrow. Flares and CMEs 15 C flares were recorded on October 19. Region 8731 managed to produce only 1 small C flare while region 8732 was quite active producing 7 C flares. Region 8737 generated a single C flare. The largest flares of the day had their origin on region 8732, an impulsive C8.7 flare at 19:41 UTC and a C7.3/1F event at 22:04 UTC. October 17-18: A filament eruption in the southeast quadrant near the central meridian was first observed in EIT images at 23:12 UTC on October 17. A coronal mass ejection was observed shortly afterwards covering the south pole and the east limb. The CME could impact earth on October 21. The background x-ray flux is at the class B8 level. Coronal holes A well placed and well defined coronal hole in the northern hemisphere will move into a geoeffective position on October 22. Forecast The geomagnetic field is expected to be quiet to unsettled on October 20. On October 21 a CME could reach the earth and cause unsettled to active conditions. A coronal stream will cause the geomagnetic field to reach unsettled to minor storm levels October 25-26. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally fair to 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 Location region numbered no. at Area Classification Comment sunspots midnight 8728 991008 3 N24W70 0130 DAO 8729 991009 N16W62 plage 8731 991011 63 N13W44 0640 FKC beta-gamma 8732 991012 29 N21W53 0190 FAI beta-gamma-delta 8733 991012 N26W89 plage 8734 991015 N17W36 plage 8735 991016 4 N19W06 0020 CRO 8736 991017 2 S21E07 0000 BXO 8737 991019 8 S15E14 0050 CAO Total number of sunspots: 109 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 (84.9 predicted, +1.1) 9905 148.4 106.4 (89.5 predicted, +4.6) 9906 169.8 137.4 (93.6 predicted, +4.1) 9907 165.6 113.5 9908 170.7 93.7 9909 135.7 70.6 9910 160.5 (1) 98.4 (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]