Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update February 18, 2000 at 04:35 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] [Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was quiet to unsettled on February 17. Solar wind speed ranged between 369 and 431 km/sec. Solar flare activity was moderate. Solar flux was 168.4, the planetary A index was 6 (3-hour Kp indices: 0013 3222, Boulder K indices: 0113 3221). Region 8862 was quiet and stable. Region 8867 was mostly unchanged and quiet. Region 8868 decayed and will likely become spotless before rotating over the west limb on Feb.19. Region 8869 developed further and could produce further minor M flares. Region 8870 was quiet and stable. Region 8871 decayed into spotless plage. Region 8872 was mostly unchanged, a repeat of yesterday's minor M flare is unlikely. Region 8874 decayed into spotless plage. Region 8875 was quiet and stable. Region 8876 decayed slowly and was quiet. Region 8877 decayed into spotless plage. Region 8878 was quiet and stable. New region 8879 rotated partly into view at the northeast limb, this region may be capable of minor M class flaring. Flares and CMEs 6 C flares and 2 M flares were observed on February 17. Region 8869 produced an M2.5/1B flare at 18:52 UTC. This flare was accompanied by a moderately strong type II sweep and a fairly unimpressive coronal mass ejection off the southwest limb. Another minor M flare in region 8872 may have been triggered by the event in region 8869. It is fairly rare that regions as small as 8872 produce as impressive long duration events as the one that peaked at 20:35 UTC as an M1.3/2N flare. This event was associated by a strong type II sweep and a full (and beautiful) halo CME which was easily visible in LASCO C2 images at 21:30 UTC. There is a 100% chance that Earth will receive an impact from this CME, the question is when and how significant the event will be. The likely impact time window is from noon on February 19 until late on February 20. If the brightness of the observed halo is an indication of the severeness of the impact and the effect on the geomagnetic field, then this will likely be the most significant CME impact in some time. Minor to very severe storming is possible (K index in the range 5-8, isolated K9 intervals are not unlikely). The above 10 MeV proton flux has been slightly enhanced since yesterday's M flares and may have peaked at just above 1 pfu. 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 February 21 or 22 and start a disturbance on February 24 or 25. Forecast The geomagnetic field is expected to be quiet to unsettled on Feb.18. Sometime during the latter half of Feb.19 or on Feb.20 a CME will impact earth and probably cause minor to severe storming. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally 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 8862 20000206 1 S06W72 0110 HSX 8863 20000208 S16W48 plage 8866 20000208 N15W53 plage 8867 20000209 8 S16W73 0100 DAO 8868 20000209 1 S23W74 0000 AXX 8869 20000210 22 S22W21 0150 DAO 8870 20000210 1 N19W14 0070 HSX 8871 20000211 S14W87 plage 8872 20000211 6 S29E02 0020 BXO 8873 20000213 S18E15 plage 8874 20000214 S08E14 plage 8875 20000215 5 S22E28 0020 CRO 8876 20000215 4 S12E33 0040 DSO 8877 20000216 S26E15 plage 8878 20000216 3 S26W55 0050 DAO 8879 20000217 1 N21E74 0110 HSX Total number of sunspots: 52 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.01 140.6 62.0 82.6 (+4.7) 1999.02 141.9 66.3 84.6 (+2.0) 1999.03 126.3 68.8 83.8 (-0.8) 1999.04 117.2 63.7 85.4 (+1.6) 1999.05 148.4 106.4 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 2000.02 165.7 (1) 93.1 (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]