Solar Terrestrial Activity Report [Image] Last update February 24, 2001 at 06:45 UT. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update February 2, 2001) - Did cycle 23 peak in April 2000?] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2001)] [Historical solar and geomagnetic data charts 1954-2000 (last update January 18, 2001)] Recent development The geomagnetic field was quiet to active on February 23. Solar wind speed ranged between 326 and 439 km/sec. Solar flare activity was low. Solar flux was 145.2, the planetary A index was 11 (3-hour K indices: 3342 3322, Boulder K indices: 3242 3212). Region 9350 rotated off the visible disk. Region 9352 reemerged with a couple of spots, no spots are visible early on Feb.24. Region 9353 decayed into spotless plage. Region 9354 developed slowly and was quiet. There is a possibility of minor M class flaring. Region 9356 was spotless all day in all available images, SEC/NOAA reports that 2 spots were observed. Regions 9357 and 9358 were quiet and stable, region 9358 is spotless early on Feb.24. Region 9359 developed slowly and could produce M class flares. Region 9360 was quiet and stable. Region 9361 was quiet and stable, no spots are visible early on Feb.24. Flares and CMEs A total of 3 C class events were observed on February 23. Region 9359 produced a C1.4 flare at 14:23 UT. A long duration C2.2 event peaked at 23:19 UT, its source was in the southeast quadrant, just east of region 9360. A coronal mass ejection was produced and could be observed in LASCO images before midnight. It's not yet clear if the CME was a full halo CME, anyway, most of the ejected material was observed over the central east limb. The background x-ray flux is at the class B3 level. Coronal holes A small, well placed coronal hole in the northern hemisphere was in a geoeffective position on February 23. A coronal hole in the southern hemisphere may have been located too far to the south to have been geoeffective when it rotated across the central meridian on Feb.23-24. Forecast The geomagnetic field is expected to be quiet to unsettled on February 24-25. There is a chance of unsettled to active conditions on February 26 due to a coronal stream. 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 9352 2001.02.15 2 S21W35 0000 AXX 9353 2001.02.16 S24W77 plage 9354 2001.02.16 18 S09W59 0250 DAO 9355 2001.02.18 N20W31 plage 9356 2001.02.18 2 S13W80 0010 CSO 9357 2001.02.18 8 S25W33 0020 BXO 9358 2001.02.18 6 S04W22 0010 BXO 9359 2001.02.20 15 N12E34 0200 EAO 9360 2001.02.21 1 S10E31 0030 HRX 9361 2001.02.22 3 S12W06 0010 BXO Total number of sunspots: 55 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.11 191.5 133.2 111.0 (+3.2) 1999.12 169.8 84.6 111.1 (+0.1) 2000.01 158.1 90.1 112.9 (+1.8) 2000.02 174.1 112.9 116.8 (+3.9) 2000.03 208.2 138.5 119.9 (+3.1) 120.8 (+0.9) 2000.04 184.2 125.5 cycle 23 peak candidate 2000.05 184.9 121.6 119.0 (-1.8) 2000.06 179.8 124.9 118.7 (-0.3) 2000.07 202.3 170.1 119.8 (+1.1) 2000.08 163.0 130.5 (119.5 predicted, -0.3) 2000.09 182.1 109.7 (117.9 predicted, -1.6) 2000.10 167.4 100.1 (116.3 predicted, -1.6) 2000.11 178.8 106.5 (114.4 predicted, -1.9) 2000.12 173.6 104.5 (111.8 predicted, -2.6) 2001.01 166.6 95.7 (108.2 predicted, -3.6) 2001.02 149.4 (1) 113.9 (2) 1) Running average based on the daily 20:00 UT 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]