Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 28, 1999 at 01:15 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 active on October 27. Solar wind speed ranged between 373 and 436 km/sec. Solar flare activity was moderate. Solar flux was 197.3, the planetary A index was 17 (3-hour Kp indices: 2334 4432, Boulder K indices: 2434 3322). Region 8737 rotated over the west limb, the region could still generate another M flare from just behind the limb over the next day. Region 8738 was quiet and stable. Region 8739 decayed slightly but remains large and complex. The region is likely to produce occasional M flares, a major flare is possible over the next few days. Region 8741 developed slowly was mostly quiet. Region 8742 was mostly unchanged and could produce M class flares. Region 8743 was quiet and stable, as were regions 8744 and 8745. New region 8746 emerged in the southeast quadrant, Flares and CMEs 3 C flares and 3 M flares were recorded on October 27. Region 8737 was the most active flare producer generating at least 2 of the 3 M class events. The first M flare of the day was an M1.0 event at 09:12 UTC. The source of the event is not clear in LASCO EIT images, either region 8739 or 8737 could have been the source. Region 8737 produced an M1.8 flare at 13:37 UTC and an M1.4 event at 15:41 UTC. A C5.3 flare at 04:30 UTC was fairly interesting. It was associated with a strong type II sweep. LASCO EIT images indicate that the flare occurred between regions 8744 and 8742 as there was a bright flash in that area at that time. No obvious CME was observed in LASCO C2, however, the CME may have been faint. If there was a CME it could impact the earth sometime between late on October 29 and noon 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 active on October 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 8737 991019 1 S13W89 0140 HSX 8738 991020 2 N17W67 0090 CSO 8739 991020 42 S12W23 0650 FKC beta-gamma-delta 8741 991022 19 S25W03 0190 EAO 8742 991023 25 N08E29 0480 EKI beta-gamma 8743 991025 3 S14W07 0020 DAO 8744 991025 5 N09E16 0010 BXO 8745 991026 2 S14E54 0150 HSX 8746 991027 4 S15E28 0010 BXO Total number of sunspots: 103 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]