Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update October 14, 1999 at 01:50 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] [NEW! Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was unsettled to minor storm on October 13. Solar wind speed ranged between 521 and 667 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 191.0, the planetary A index was 26 (3-hour Kp indices: 4354 4333, Boulder K indices: 4353 3343). Regions 8716 and 8719 were quiet and stable, region 8719 will rotate over the west limb today. Region 8720 decayed into spotless plage, as did region 8721. Region 8725 decayed slowly and was quiet. Region 8727 developed slowly and was quiet. Region 8728 developed slowly. Magnetic gradients within the region are still fairly weak and an M flare is not likely over the next day or so. Sub flaring has increased significantly and may be indicative of more substantial flare activity in 2-3 days. Region 8729 developed further but is a fairly simple region with no large sunspots. Should further development take place M flaring will become possible. Region 8731 is developing fairly quickly and has minor and perhaps major M class flaring potential. Region 8732 developed quickly and has minor M class flaring potential. Region 8733 was quiet and stable. An active region could be emerging near region 8733. An active region is approaching the southeast limb and should rotate into view in 1-2 days. Flares and CMEs A total of 6 C flares were recorded on October 13. Region 8729 produced a C1.6 flare at 23:16 UTC. Regions 8731 and 8732 produced 2 C flares each with the most energetic a C2.8 flare at 13:41 UTC from region 8732. The most interesting event of the day was a large filament eruption in the northern hemisphere. The event started at 07:13 in the northeast quadrant. Development was slow at first and spread towards the southwest crossing the central meridian with the most intense activity between 09 and 11h UTC. LASCO C2 observed a coronal mass ejection starting at 10:06 UTC over the north pole. Material was later evident in all directions, and there is a fairly high chance that the earth will receive a weak impact from this CME on October 16. The background x-ray flux is at the class B7 level. Coronal holes A large coronal hole mainly in the southern hemisphere but stretching across the equator and into the northern hemisphere in the eastern parts, was in a geoeffective position October 9-13. Forecast The geomagnetic field is expected to be unsettled to minor storm on October 14 with a chance of major storm intervals late in the day. Unsettled to major storm is likely on October 15-16 as the most well defined and well placed part of a large coronal hole will have been in a geoeffective position 3 days earlier. A CME impact is possible on October 16, however, it could catch up with the tail end of the coronal stream currently affecting the geomagnetic field. 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 8716 991002 2 N22W74 0140 HAX 8719 991003 1 S20W84 0060 HAX 8720 991003 N12W63 plage 8721 991003 S15W77 plage 8723 991004 N20W38 plage 8725 991005 1 S25W39 0010 HSX 8726 991006 S19W70 plage 8727 991007 9 N21W24 0040 BXO 8728 991008 26 N23E15 0520 FKO 8729 991009 30 N11E17 0110 CRO 8730 991010 S11W33 plage 8731 991011 38 N11E37 0620 EKO beta-gamma 8732 991012 10 N19E28 0230 DSO 8733 991012 3 N24W13 0010 BXO 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 149.4 (1) 66.2 (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]