Solar Terrestrial Activity Report [Image] Last update April 9, 2002 at 03:50 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update April 2, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April, 2002)] [Historical solar and geomagnetic data charts 1954-2001 (last update January 12, 2002)] Recent development The geomagnetic field was quiet to unsettled on April 8. Solar wind speed ranged between 335 and 408 km/sec. Solar flare activity was low. Solar flux was 207.9, the planetary A index was 5 (3-hour K indices: 1011 2321, Boulder K indices: 0011 1211). Region 9885 rotated quietly off the visible disk. Region 9886 decayed further and no spots were visible by early afternoon. Region 9887 decayed further losing penumbral area in both the leading and trailing spots sections. Region 9888 decayed further and could become spotless before rotating over the southwest limb early on April 11. Region 9892 was spotless all day in all available images. Region 9893 still has a magnetic delta in the trailing spots section, however, the delta has weakened over the last 24 hours and could soon disappear. The region decayed otherwise losing most of its intermediate spots. A minor m class flare is possible as long as the magnetic delta persists. Region 9896 was quiet and stable. Region 9897 decayed further and could become spotless late on April 9. Region 9898 was mostly quiet and stable. Region 9899 was the most interesting region producing several flares and having the tightest magnetic gradients of the visible regions. Magnetograms show that the positive polarity inside the main penumbra has increased its coverage. Negative polarity areas have emerged several places near the main penumbra and further minor M class flares are possible. Region 9900 developed slowly and could produce minor M class flares. Region 9901 developed slowly (the region still appears to be part of region 9893 with the leading positive magnetic polarity shared with the positive polarity in the magnetic delta in the trailing section of region 9893). Region 9902 was quiet and stable. New region 9903 rotated into view at the northeast limb. Flares and CMEs A total of 13 C class events were recorded on April 8. Region 9899 produced a C2.1 flare at 00:19, a C4.7 flare at 03:04 and a C2.1 flare at 11:23 UTC. Region 9901 generated a C5.1 flare at 01:50 and a C2.1 flare at 03:49 UTC. Region 9898 was the source of a C2.0 flare at 05:26 and a C2.3 flare at 17:34 UTC. Region 9887 generated a C1.5 flare at 12:02 UTC while region 9888 managed a C2.1 flare at 13:49 UTC. Region 9899 was the origin of an impulsive M2.1 flare at 00:42 UTC on April 9. A type II radio sweep was recorded as well but LASCO C3 images do not indicate any significant CME produced by this event. The background x-ray flux is at the class B9 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on April 9-11. 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 9885 2002.03.27 4 N13W93 0120 HSX 9886 2002.03.29 5 N14W80 0050 BXO area too large 9887 2002.03.29 6 N02W69 0420 EAO 9888 2002.03.29 4 S12W59 0110 CSO area way too large 9889 2002.03.31 S20W58 plage 9891 2002.04.02 S08W87 plage 9892 2002.04.02 2 N05W19 0010 CRO actually spotless 9893 2002.04.03 27 N18E13 0450 FHI beta-gamma-delta 9894 2002.04.05 N14W48 plage 9895 2002.04.05 N06E19 plage 9896 2002.04.05 1 S11E34 0080 HSX 9897 2002.04.06 6 S02W30 0030 DSO 9898 2002.04.06 4 S19E40 0010 CRO 9899 2002.04.06 3 N18E46 0220 CKO beta-gamma 9900 2002.04.07 20 S29W06 0150 EAI beta-gamma 9901 2002.04.07 17 N19E24 0130 DAI still thought to be part of region 9893 9902 2002.04.07 3 N13E64 0090 CSO 9903 2002.04.08 3 N19E74 0060 DSO Total number of sunspots: 105 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 2001.02 146.6 80.6 104.0 (-4.7) 2001.03 177.7 113.5 104.8 (+0.8) 2001.04 177.7 107.7 107.5 (+2.7) 2001.05 147.1 96.6 108.6 (+1.1) 2001.06 173.0 134.0 109.8 (+1.2) 2001.07 131.3 82.2 111.7 (+1.9) 2001.08 162.9 106.8 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 (112.7 predicted, -1.4) 2001.11 210.6 106.5 (111.5 predicted, -1.2) 2001.12 235.1 132.2 (108.1 predicted, -3.4) 2002.01 226.6 113.9 (104.8 predicted, -3.3) 2002.02 205.0 108.0 (103.4 predicted, -1.4) 2002.03 179.5 98.1 (99.1 predicted, -4.3) 2002.04 209.6 (1) 56.5 (2) (93.2 predicted, -5.9) 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 25-45% 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]