Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 28, 1999 at 03:40 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update December 2, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update December 2, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 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 December 27. Solar wind speed ranged between 368 and 478 km/sec. Solar flare activity was moderate. Solar flux was 161.7, the planetary A index was 6 (3-hour Kp indices: 3222 0120, Boulder K indices: 3222 0110). Region 8804 decayed slowly, the region will rotate off the visible disk late on Dec.29. Region 8806 lost some of its areal coverage, however, the number of spots increased and the region is still large and complex. A major flare remains a possibility until the region rotates over the west limb on Dec.30/31. Region 8807 decayed into spotless plage. Region 8809 was quiet and stable. Region 8810 developed further and could be capable of producing a major flare. Region 8811 decayed into spotless plage. Active regions are approaching the northeast limb, a couple of those regions could be interesting. A large loop behind the northeast limb is extending almost to the north pole. Flares and CMEs 6 C flares and 2 M flares were recorded on December 27. Region 8806 produced 4 minor C flares and both M flares. The first was an M1.0/1N event at 01:54 UTC. It was associated with a strong type II sweep and an unimpressive coronal mass ejection off the northwest limb. An impulsive M2.0 event was observed at 12:06 UTC. Region 8806 was the source of an M4.5 flare at 00:48 UTC on Dec.28. A prominence eruption was observed at the northeast limb at 20:36 in LASCO EIT images. A huge coronal mass ejection was observed behind the northeast limb at 23h UTC in LASCO C2 (the CME must have started earlier as it clearly had been in progress for some time, missing frames prevents a more exact start time from being determined). The background x-ray flux is at the class B6 level. Coronal holes A large trans equatorial coronal hole will rotate into a geoeffective position on December 28 - January 1, the coronal hole is not quite as extensive as it was the last time it was visible one solar rotation ago. Forecast The geomagnetic field is expected to be quiet to unsettled on December 28-30. A coronal stream will reach Earth on December 31 and cause unsettled to minor storm conditions until January 4, probably with quiet to active conditions towards the end of that interval. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally 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 8804 991216 3 S18W64 0190 HSX 8806 991217 48 N20W54 0810 FHC beta-gamma-delta 8807 991218 N11W50 plage 8809 991224 7 N22E27 0040 DAO 8810 991224 11 N38E44 0410 FKO 8811 991225 S28W42 plage Total number of sunspots: 69 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 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 63.7 85.4 (+1.6) 9905 148.4 106.4 90.4 (+5.0) 9906 169.8 137.7 (92.5 predicted, +2.1) 9907 165.6 113.5 (94.0 predicted, +1.5) 9908 170.7 93.7 (98.9 predicted, +4.9) 9909 135.7 70.6 9910 164.8 116.4 9911 191.5 132.7 9912 174.2 (1) 110.1 (2) 1) Running average based on the daily 20:00 UTC solar flux measurement at 2800 MHz by DRAO. 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]