Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 20, 1999 at 03:00 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 19. Solar wind speed ranged between 382 and 442 km/sec. Solar flare activity was low. Solar flux was 206.9, the planetary A index was 4 (3-hour Kp indices: 1002 2211, Boulder K indices: 1112 3311). Region 8794 decayed into spotless plage. Region 8797 decayed further and appears to be spotless early on Dec.20. Region 8798 is still a complex region capable of M class flaring, however, the region has lost some area and a few spots and could be slowly decaying. Region 8800 decayed into spotless plage. Region 8803 was quiet and stable, like nearby region 8798 it could be in slow decay. Region 8804 was quiet and stable. The region has a huge leader spot and seems to be developing slowly. Region 8805 decayed into spotless plage. Region 8806 is a large region capable of producing major flares. Early on Dec.20 it appears to have developed a magnetic delta configuration, further enhancing the probability of a major flare. Region 8807 is a small region but is unstable and could produce further C flares. New region 8808 emerged in the southeast quadrant near the central meridian. Flares and CMEs 9 C flares were recorded on December 19. Region 8794 produced a C2.1 flare at 19:31 UTC. Region 8798 was the source of a C2.0 flare at 20:15 UTC while region 8807 managed a C2.6 flare at 23:13 UTC. Region 8806 continued to be the most active flare producer with a total of 4 C flares, the largest a C5.6 flare at 22:34 UTC. The background x-ray flux is at the class C1 level. Coronal holes A weak coronal hole in the northern hemisphere may have been in a geoeffective position on December 18-20. Forecast The geomagnetic field is expected to be mostly quiet on December 20. Quiet to unsettled, perhaps with active intervals, is likely on DEcember 21-22. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally fair to good. 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 8792 991208 N20W76 plage 8794 991209 S16W66 plage 8796 991213 S25W84 plage 8797 991213 1 S32W65 0000 AXX 8798 991213 41 S13W06 0500 EKI beta-gamma-delta 8800 991214 N10W09 plage 8801 991214 S22W65 plage 8802 991216 S23W35 plage 8803 991216 13 S13W16 0070 DAO 8804 991216 3 S19E43 0250 CHO 8805 991217 N18W54 plage 8806 991217 20 N19E50 0890 FKC beta-gamma-delta 8807 991218 4 N11E57 0040 CSO 8808 991219 2 S19E06 0000 BXO Total number of sunspots: 84 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 167.3 (1) 76.4 (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]