Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 27, 1999 at 03:55 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 on December 26. Solar wind speed ranged between 370 and 533 km/sec. A weak solar wind shock was observed at ACE at 21:34 UTC. The interplanetary magnetic field strengthened towards midnight and was for some time moderately to strongly southwards. This caused unsettled to active conditions early on Dec.27. The source of the shock could be the first CME observed on Dec.22, however, unless there is a second shock during the first half of Dec.27, the most likely candidate would be the second CME observed on Dec.22. Solar flare activity was low. Solar flux was 177.0, the planetary A index was 2 (3-hour Kp indices: 1000 0111, Boulder K indices: 1000 0101). Region 8804 was quiet and stable. Region 8806 decayed slowly but remains capable of producing a major flare. Region 8807 decayed further, the region is spotless early on Dec.27. Region 8809 was quiet and stable. Region 8810 developed slowly and is likely to produce further C flares. An M flare is possible as well. Region 8811 was quiet and stable, the region appears to be spotless early on Dec.27. An active region is emerging in the southeast quadrant. Flares and CMEs 9 C flares were recorded on December 26, most of them optically unaccounted. Region 8806 produced 2 C flares and region 8810 was the source of 1 C flare, none of them were particularly interesting. Region 8806 generated an M1.0 flare at 01:54 UTC and a minor coronal mass ejection was observed off the northwest limb following the event. 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 2. Forecast The geomagnetic field is expected to be quiet to active on December 27 with a chance of minor storm intervals. A coronal stream will reach Earth on December 31 and cause unsettled to minor storm conditions until January 4 or 5. 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 5 S17W51 0260 CHO 8806 991217 39 N21W41 0900 FKC beta-gamma-delta 8807 991218 5 N11W37 0010 BXO 8808 991219 S18W86 plage 8809 991224 7 N21E41 0030 BXO 8810 991224 8 N36E54 0350 EKO 8811 991225 1 S28W29 0000 AXX Total number of sunspots: 65 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 174.7 (1) 106.6 (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]