Solar Terrestrial Activity Report [Image] Last update September 22, 2001 at 04:00 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update September 1, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 1, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 1, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update July 27, 2001)] Recent development The geomagnetic field was quiet on September 21. Solar wind speed ranged between 312 and 380 km/sec. Solar flare activity was low. Solar flux was 238.6 (average solar flux for September will likely end up significantly higher than for any other month in cycle 23), the planetary A index was 5 (3-hour K indices: 1002 2222, Boulder K indices: 2011 3332). Region 9616 decayed slowly and quietly. Region 9619 decayed into spotless plage. Regions 9620 and 9621 were mostly unchanged with region 9620 flaring occasionally. Region 9622 was mostly quiet and stable. Region 9624 was quiet and stable, as were regions 9626 and 9627. Region 9625 decayed and was spotless by early evening. Region 9628 did not change much and has a magnetic delta configuration within the trailing spots section. Major flares are possible. Region 9629 was mostly unchanged and quiet. Region 9630 decayed into spotless plage. Region 9631 developed further and could produce minor M class flares. Region 9632 developed slowly and has a large penumbra containing a magnetic delta. The region could produce major flares by itself or together with nearby region 9628. An interesting region is about to rotate into view at the northeast limb. Flares and CMEs A total of 5 C class events were observed on September 21. Region 9628 produced a C7.8 flare at 05:10 and a C3.8 flare at 18:51 UTC. Region 9631 was the source of an M1.5 flare at 18:17 UTC. September 20: A partial halo CME was observed in LASCO C3 images beginning at 20:18 UTC at the northwest limb, its source was likely an M1 flare in region 9631. This CME could influence the geomagnetic field late on September 23 or on September 24. An earlier CME off the southern limbs had this CME appearing as a full halo CME. The background x-ray flux is at the class C1-C2 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on September 22-23. 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 Location region numbered no. at Area Classification Comment sunspots midnight 9616 2001.09.11 11 S12W51 0120 FAO beta-gamma 9617 2001.09.12 N10W47 plage 9619 2001.09.13 N17W80 plage 9620 2001.09.16 10 N11E04 0140 DKO 9621 2001.09.16 6 N14E07 0150 DAO 9622 2001.09.17 17 N12W18 0080 DAO 9623 2001.09.17 N21W09 9624 2001.09.17 2 N03E14 0090 HSX 9625 2001.09.18 1 S30W51 0000 AXX 9626 2001.09.18 7 N25W01 0030 CSO 9627 2001.09.18 3 N03E30 0050 CAO 9628 2001.09.18 44 S18E38 0790 FKC beta-gamma-delta 9629 2001.09.19 9 N26E11 0050 DAO 9630 2001.09.20 N27W49 plage 9631 2001.09.20 15 N09W24 0120 DAC beta-gamma 9632 2001.09.20 13 S17E56 0640 DKI beta-gamma-delta Total number of sunspots: 138 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.03 208.2 138.5 119.9 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.7 2000.08 163.0 130.5 118.6 (-1.1) 2000.09 182.1 109.7 116.3 (-2.3) 2000.10 167.4 99.4 114.5 (-1.8) 2000.11 178.8 106.8 112.8 (-1.7) 2000.12 173.6 104.4 112.1 (-0.7) 2001.01 166.6 95.6 108.8 (-3.3) 2001.02 146.6 80.6 104.1 (-4.7) 2001.03 177.7 113.5 (104.5 predicted, +0.4) 2001.04 177.7 108.2 (106.0 predicted, +1.5) 2001.05 147.1 97.3 (105.5 predicted, -0.5) 2001.06 173.0 134.0 (103.8 predicted, -1.7) 2001.07 131.3 82.2 (102.5 predicted, -1.3) 2001.08 162.9 106.8 (103.1 predicted, +0.6) 2001.09 220.7 (1) 147.2 (2) (102.5 predicted, -0.6) 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] [StudyWeb]