Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 27, 1999 at 01:35 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] [Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was quiet to unsettled on October 26. Solar wind speed ranged between 401 and 577 km/sec gradually decreasing all day Solar flare activity was moderate. Solar flux was 189.4, the planetary A index was 9 (3-hour Kp indices: 1323 3322, Boulder K indices: 1323 3331). Region 8737 will rotate behind the west limb today, the region could generate another M flare from just behind the limb over the next 1-2 days. Region 8738 was quiet and stable. Region 8739 developed further and is large and complex. The region is likely to produce further M flares, major flares are possible the next few days. Region 8741 decayed slowly and was quiet. Region 8742 developed further and could produce M class flares. Region 8743 developed slowly and was quiet. Region 8744 was quiet and stable. New region 8745 rotated into view at the southeast limb. Further active regions are approaching both the northeast and southeast limbs. Flares and CMEs 12 C flares and 3 M flares were recorded on October 26. Region 8739 was the most active region producing 3 C flares and 2 M flares (long duration M1.2 and M2.3 event which peaked at 07:45 and 18:42 UTC respectively). The most energetic event of the day was caused by region 8737 at the west limb when it produced an M3.7 flare peaking at 21:25 UTC. A coronal mass ejection was associated with the latter event while none of the M class eruptions in region 8739 produced any noticable CMEs. Region 8739 did produce one event that may have been associated with a coronal mass ejection, a subflare at 22:14 UTC coincided with the start of a moderately strong type IV sweep. If there was a CME it will likely impact earth on October 30. October 25: A large filament in the southern hemisphere erupted resulting in a partial halo coronal mass ejection over the south pole and most of the southwest and southeast limbs, the CME was first visible in LASCO C2 at 14:26 UTC. There is a 25-40% chance the CME could impact the earth on October 28. The background x-ray flux is at the class C1-C2 level. Coronal holes A small, isolated coronal hole in the northern hemisphere was in a geoeffective position on October 26. Forecast The geomagnetic field is expected to be quiet to unsettled October 27-28. A CME could impact the earth on October 28 and cause unsettled to minor storm conditions. A coronal stream could reach the earth on October 29 and cause unsettled to active intervals. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally poor and improving. 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 8736 991017 S25W84 plage 8737 991019 5 S15W78 0360 EAO 8738 991020 3 N17W53 0010 BXO 8739 991020 62 S11W10 0800 FKC beta-gamma-delta 8741 991022 11 S25E09 0140 EAO 8742 991023 24 N09E43 0480 EKI beta-gamma 8743 991025 8 S18E08 0050 BXO 8744 991025 5 N07E30 0000 BXO 8745 991026 2 S14E66 0170 HAX Total number of sunspots: 120 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 162.3 (1) 134.3 (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]