Solar Terrestrial Activity Report [Image] Last update December 18, 2001 at 04:05 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, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update October 16, 2001)] Recent development The geomagnetic field was quiet to active on December 17. Solar wind speed ranged between 424 and 558 km/sec. Solar flare activity was low. Solar flux was 205.5, the planetary A index was 15 (3-hour K indices: 2334 4432, Boulder K indices: 1233 3332). Region 9732 was quiet and stable and will rotate off the visible disk late today. Region 9733 decayed slowly and was mostly quiet. Minor M class flares are still possible. Region 9734 was spotless early in the day, then reemerged with a couple of spots. Region 9737 was quiet and stable. Region 9738 developed slowly and quietly. Region 9739 developed slowly and could produce isolated minor M class flares. Region 9741 was quiet and stable. Region 9742 did not change much and remains capable of M class flare production. Region 9743 was quiet and stable, as was region 9744. A small spotted region has rotated into view at the northeast limb. Flares and CMEs A total of 2 C class events were recorded on December 17. Region 9733 produced a C2.0 flare at 04:05 UTC. The background x-ray flux is at the class C1 level. Coronal holes An isolated coronal hole in the southern hemisphere will rotate across the central meridian on December 20 and could be partially geoeffective then. Forecast The geomagnetic field is expected to be quiet to unsettled on December 18-20. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to 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 9732 2001.12.07 1 N02W75 0060 HSX 9733 2001.12.08 44 N14W48 0420 EAI beta-gamma 9734 2001.12.09 2 S15W23 0020 BXO 9737 2001.12.10 3 S28W37 0050 DAO 9738 2001.12.12 18 S18E01 0120 EAO 9739 2001.12.13 17 S13W57 0440 DKO beta-gamma 9740 2001.12.13 S06E03 plage 9741 2001.12.13 6 N05E17 0050 DAO 9742 2001.12.15 17 N08E51 0340 DKI beta-gamma 9743 2001.12.16 4 S12E59 0160 HAX 9744 2001.12.16 3 S06E11 0030 CAO Total number of sunspots: 115 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2000.10 167.4 99.4 114.5 (-1.8) 2000.11 178.8 106.8 112.7 (-1.8) 2000.12 173.6 104.4 112.0 (-0.7) 2001.01 166.6 95.6 108.7 (-3.3) 2001.02 146.6 80.6 104.1 (-4.6) 2001.03 177.7 113.5 104.8 (+0.7) 2001.04 177.7 107.7 107.6 (+2.8) 2001.05 147.1 96.6 108.7 (+1.1) 2001.06 173.0 134.0 (108.5 predicted, -0.2) 2001.07 131.3 82.2 (108.1 predicted, -0.4) 2001.08 162.9 106.8 (108.7 predicted, +0.6) 2001.09 233.2 150.7 (108.1 predicted, -0.6) 2001.10 207.6 125.6 (105.3 predicted, -2.8) 2001.11 210.6 106.5 (103.7 predicted, -1.6) 2001.12 224.7 (1) 117.5 (2) (100.3 predicted, -3.4) 1) Running average based on the daily 20:00 UT solar flux value at 2800 MHz. 2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News]