Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 29, 1999 at 01:40 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 28. Solar wind speed ranged between 351 and 481 km/sec. The interplanetary magnetic field strengthened towards the end of the day and swung southwards and caused unsettled to active conditions. Solar flare activity was moderate. Solar flux was 150.4, the planetary A index was 6 (3-hour Kp indices: 0311 2223, Boulder K indices: 1321 2223). Region 8804 was quiet and stable and will rotate off the visible disk late today. Region 8806 decayed fairly quickly but maintained its magnetic delta configuration. A major flare is possible before the region rotates over the west limb late on Dec.30. Region 8809 was quiet and stable. Region 8810 was mostly quiet and stable. Active regions are approaching the northeast limb, one of them is very close to the equator and will probably rotate into view today. A larger and more interesting region is likely 3-5 days behind the east limb. Flares and CMEs 5 C flares and 1 M flare were recorded on December 28. Region 8806 produced 4 C flares and 1 M flare. The latter was an M4.5/2B event associated with a strong type II sweep. An optically unaccounted C2.8 flare at 01:20 was associated with a weak type IV sweep. The background x-ray flux is at the class B4 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 29-30 with a chance of active intervals. 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 2 S17W78 0170 HSX 8806 991217 20 N19W66 0520 FHI beta-gamma-delta 8807 991218 N11W64 plage 8809 991224 4 N22E15 0040 DAO 8810 991224 11 N38E32 0400 FKO 8811 991225 S28W54 plage Total number of sunspots: 37 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]