Solar Terrestrial Activity Report [Image] Last update April 10, 2002 at 04:30 UTC. Last minor update posted at 19:49 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 9. Solar wind speed ranged between 291 and 350 km/sec. Solar flare activity was moderate. Solar flux was 205.0, the planetary A index was 6 (3-hour K indices: 2011 2332, Boulder K indices: 1010 0211). Region 9887 is rotating quietly over the northwest limb. Region 9888 decayed and became spotless by late afternoon. Region 9893 developed slowly with new negative polarity areas emerging near the leading penumbra. There is still a magnetic delta in the trailing spots section and the region is capable of producing minor M class flares. Region 9896 was quiet and stable. Region 9897 decayed slowly and quietly. Region 9898 was quiet and stable. Region 9899 was the most active region during the day but appears to have calmed over the last hours. Another minor M class flare is possible. Region 9900 developed a magnetic delta structure in the central part of the region. A minor M class flare is possible. Region 9901 developed slowly and quietly (no distinct separation from region 9893 can be observed). Region 9902 was quiet and stable. Region 9903 developed slowly and was somewhat unstable. New region 9904 emerged over the central meridian in the southern hemisphere and was fairly active during the afternoon. Comment added at 13:02 UTC on April 10: Region 9893 produced an impulsive major M8.2 flare at 12:31 UTC. The center of the flare was located where the trailing magnetic delta structure is, which currently is almost over the central meridian. If there was a CME associated with this flare it will almost certainly be directed towards the Earth. Another update will follow when LASCO images for the first 2 hours after the event are available, provided that there is a significant CME. Comment added at 19:49 UTC: The above mentioned flare was associated with a CME which was first observed in LASCO C2 images at 13:27 UTC. This halo CME did not appear to be very large and it is difficult to estimate how strong a geomagnetic disturbance it will cause on April 13. Flares and CMEs A total of 5 C and 2 M class events were recorded on April 9. Region 9899 produced an impulsive M2.1 flare at 00:42 UTC. A type II radio sweep was recorded as well but LASCO C3 images did not indicate any significant CME produced by this event. Region 9899 produced a long duration C7.9/1F event peaking at 07:36 and an impulsive M1.1 flare at 13:02 UTC. Region 9903 generated a C6/1F flare peaking at 06:07 UTC. Region 9904 was the source of a C2.2 flare at 17:35 and a C4.1 flare at 19:16 UTC. The background x-ray flux is at the class C1 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 10-12. 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 9887 2002.03.29 5 N04W82 0250 EAO 9888 2002.03.29 2 S11W79 0040 CSO now spotless 9889 2002.03.31 S20W71 plage 9892 2002.04.02 N05W32 plage 9893 2002.04.03 25 N19W00 0490 EAI beta-gamma-delta 9894 2002.04.05 N14W61 plage 9895 2002.04.05 N06E06 plage 9896 2002.04.05 2 S11E21 0100 HSX 9897 2002.04.06 2 S02W43 0020 CSO 9898 2002.04.06 4 S19E25 0010 BXO 9899 2002.04.06 6 N18E33 0190 DSO beta-gamma 9900 2002.04.07 20 S29W19 0180 EAI beta-gamma-delta 9901 2002.04.07 11 N19E11 0200 DAI still thought to be part of region 9893 9902 2002.04.07 4 N13E54 0120 ESO 9903 2002.04.08 4 N19E61 0050 CAO 9904 2002.04.09 7 S16W07 0060 CAO Total number of sunspots: 92 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) 2002.04 209.0 (1) 63.6 (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]