Solar Terrestrial Activity Report [Image] Last update February 20, 2000 at 03:20 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update February 3, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 3, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 3, 2000)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to unsettled on February 19. Solar wind speed ranged between 339 and 393 km/sec. Solar flare activity was moderate. Solar flux was 144.8, the planetary A index was 4 (3-hour K indices: 0023 0111, Boulder K indices: 1123 1212). Regions 8862 and 8867 rotated off the visible disk. Region 8869 developed fairly quickly and is now capable of producing major flares. Region 8870 was quiet and stable, as was region 8872. Regions 8875, 8876, 8878 and 8879 were all quiet and stable. Region 8877 once again decayed into spotless plage. A small region is at the southeast limb while another small but somewhat more active region is at the northeast limb. Flares and CMEs 5 C flares and 1 M flare were recorded on February 19 with region 8869 producing all the activity. The most significant flares were an impulsive C8.5 flare at 06:33 UTC and a long duration M1.3/1N event peaking at 15:54 UTC. No new LASCO images have become available since early on Feb.19 and it's difficult to tell for certain whether or not the M flare was accompanied by a coronal mass ejection. Early on February 20 region 8869 has produced another C8.5 flare and several smaller C flares. The background x-ray flux is at the class B7 level. Coronal holes A trans equatorial coronal hole will rotate into a geoeffective position on February 22 or 23 and start a geomagnetic disturbance on Feb.25 or 26. Forecast The geomagnetic field is expected to be quiet to severe storm on February 20 due to an expected CME impact from the full halo coronal mass ejection observed on February 17 in region 8872. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair. 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 8869 44 S20W49 0300 EAI beta-gamma 8870 1 N18W40 0070 HSX 8872 3 S31W22 0000 AXX 8874 S09W13 plage 8875 2 S21W01 0000 BXO 8876 4 S12E06 0020 BXO 8877 S22W03 plage 8878 1 S25W85 0000 AXX 8879 20000217 1 N22E49 0200 HSX Total number of sunspots: 56 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.01 140.6 62.4 82.6 (+4.8) 1999.02 141.9 66.1 84.6 (+2.0) 1999.03 126.3 69.1 83.8 (-0.8) 1999.04 117.2 63.9 85.4 (+1.6) 1999.05 148.4 106.3 90.4 (+5.0) 1999.06 169.8 137.7 93.0 (+2.6) 1999.07 165.6 113.5 94.4 (+1.4) 1999.08 170.7 93.7 (97.4 predicted, + 3.0) 1999.09 135.7 70.9 (102.4 predicted, +5.0) 1999.10 164.8 116.4 (107.5 predicted, +5.1) 1999.11 191.5 132.7 1999.12 169.8 86.4 2000.01 158.1 90.2 2000.02 163.3 (1) 102.4 (2) 1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz.. 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]