Solar Terrestrial Activity Report [Image] Last update October 25, 2001 at 04:10 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update October 3, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update October 3, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update October 3, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update October 16, 2001)] Recent development The geomagnetic field was quiet on October 24. Solar wind speed ranged between 352 and 461 km/sec. The halo CME observed on October 22 did not arrive as early as had been expected. ACE data now indicates an arrival sometime today. Solar flare activity was low. Solar flux was 238.7, the planetary A index was 3 (3-hour K indices: 1001 1211, Boulder K indices: 2111 2210). Region 9667 decayed and was spotless by early afternoon. SEC/NOAA amazingly managed to include this region in the spot count (counting 10 spots for a region) even though they assigned zero spots to the region! Region 9669 decayed slowly and quietly. Region 9670 decayed slowly and was quiet. A minor M class flare is possible. Region 9671 decayed and was spotless by late afternoon. Region 9672 developed slowly and remains capable of producing a major flare, possibly even an X class flare. Region 9673 was quiet and stable, as were regions 9675 and 9676. Region 9674 was spotless all day in all available images. Region 9677 was quiet and stable. Region 9678 continued to develop quickly and could soon become capable of producing a major flare. This is currently the most active region on the visible disk. Region 9679 developed slowly and quietly. Region 9680 decayed into spotless plage. A fairly large region is rotating into view at the northeast limb, this could be the region which was the source of a large backsided halo CME some days ago. Flares and CMEs A total of 11 C class events were recorded on October 24. Region 9672 produced a C2.8 flare at 10:58 and a C2.0 flare at 17:11 UTC. Region 9669 generated a C3.8 flare at 14:18 UTC. Region 9678 was the source of a C6.3 long duration event peaking at 18:41 UTC. Region 9680 managed a C3.4 flare at 22:41 UTC. October 22: Region 9672 was the source of a major M6.7/2N long duration event peaking at 15:08 (with associated weak type IV and moderate type II radio sweeps) and a major X1.2/2B flare at 17:59 UTC (with an associated weak type II radio sweep). A large and bright full halo CME was observed in LASCO C3 images after the M6 event. This CME will impact Earth on October 25. The background x-ray flux is at the class C1 level. Coronal holes A coronal hole in the northern hemisphere was in a geoeffective position on October 24-25. A small coronal hole in the southern hemisphere could rotate into a geoeffective position on October 25-26. Forecast The geomagnetic field is expected to be quiet to major storm on October 25. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to very 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 Location region numbered no. at Area Classification Comment sunspots midnight 9667 2001.10.14 N27W61 plage 9669 2001.10.15 7 N14W51 0050 DAO 9670 2001.10.16 28 S18W34 0370 FAI beta-gamma 9671 2001.10.17 3 N16W62 0010 BXO now spotless 9672 2001.10.18 26 S19W13 0490 DKI beta-gamma-delta 9673 2001.10.18 4 N02W09 0130 CAO 9674 2001.10.19 1 S08W32 0010 AXX actually spotless 9675 2001.10.20 2 S13E15 0020 CSO 9676 2001.10.20 2 N16E18 0050 HSX 9677 2001.10.21 11 N19E19 0040 DAO 9678 2001.10.23 22 N07E34 0140 DAI beta-gamma 9679 2001.10.23 4 S11E46 0030 CRO 9680 2001.10.23 N22E48 plage Total number of sunspots: 110 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 2000.09 182.1 109.7 116.3 (-2.3) 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 (107.7 predicted, +2.9) 2001.05 147.1 96.6 (108.1 predicted, +0.4) 2001.06 173.0 134.0 (106.3 predicted, -1.8) 2001.07 131.3 82.2 (105.1 predicted, -1.2) 2001.08 162.9 106.8 (105.7 predicted, +0.6) 2001.09 233.2 150.7 (105.1 predicted, -0.6) 2001.10 201.6 (1) 146.7 (2) (102.3 predicted, -2.8) 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]