Solar Terrestrial Activity Report [Image] Last update May 10, 2000 at 04:25 UTC. Minor update posted at 21:33 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update May 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update May 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update April 12, 2000)] Recent development The geomagnetic field was quiet to unsettled on May 9. Solar wind speed ranged between 328 and 371 km/sec. Solar flare activity was low. Solar flux was 149.5, the planetary A index was 11 (3-hour K indices: 2323 3333, Boulder K indices: 2333 2321). Region 8980 was quiet and stable. Region 8982 reemerged and has been developing at a slow to moderate pace. C class flares are becoming possible. Region 8984 decayed into spotless plage. Regions 8983, 8986 and 8987 were mostly quiet and stable. Region 8989 developed further and seems to have a weak magnetic delta configuration. Minor M class flares are possible. Region 8990 was mostly unchanged and could produce additional C flares. Region 8991 rotated fully into view and could be capable of C class flare production. New region 8992 rotated into view at the northeast limb. Comment added at 21:33 UTC on May 10: Region 8990 was the source of a long duration C8.7 event peaking at 19:41 UTC. The event was accompanied by a strong type II sweep and likely a significant coronal mass ejection. Although it's a bit too early to tell from LASCO images, region 8990 is in a position from where CMEs easily could impact Earth. A better evaluation of the possible CME impact will have to wait until the daily update early on May 11. Flares and CMEs A total of 8 C flares were observed on May 9. Region 8990 produced a C1.8 flare at 03:06 UTC. Region 8983 generated a C2.0 flare at 12:12 UTC. Region 8991 was the source of a C1.8 flare at 18:36 UTC. Region 8989 became quite active during the latter half of the day producing a C9.2 flare at 17:40, a C2.2 flare at 19:26 and a C1.6 flare at 20:42 UTC. May 8: A large filament eruption across the central meridian in the southern hemisphere was in progress at 06:12 UTC in LASCO EIT images. A partial halo coronal mass ejection was observed from 06:48 UTC in LASCO C2 images. There is a possibility of a terrestrial impact on May 11. The background x-ray flux is at the class B6 level. Coronal holes A small well placed coronal hole in the southern hemisphere was in a geoeffective position on May 8-9. Forecast The geomagnetic field is expected to be quiet to unsettled on May 10. There is a chance of minor effects from a coronal stream on May 11-12. A CME could impact Earth on May 11 causing unsettled to minor storm intervals. 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 8980 20000428 1 S15W76 0010 AXX 8981 20000501 S22W69 plage 8982 20000503 4 S20W60 0020 CSO 8983 20000504 6 N27W07 0010 BXO 8984 20000505 S13W41 plage 8985 20000505 N12W01 plage 8986 20000505 8 S24E07 0010 BXO 8987 20000507 6 N12W17 0010 BXO 8988 20000507 N08W30 plage 8989 20000507 14 N17E12 0160 DAI beta-gamma-delta 8990 20000507 14 N14E33 0040 CSO 8991 20000508 5 N15E59 0080 CSO 8992 20000509 1 N09E72 0050 HAX Total number of sunspots: 59 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.04 117.2 63.9 85.5 (+1.7) 1999.05 148.4 106.3 90.5 (+5.0) 1999.06 169.8 137.7 93.1 (+2.6) 1999.07 165.6 113.5 94.5 (+1.4) 1999.08 170.7 93.7 97.4 (+2.9) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.7 (+5.4) 1999.11 191.5 133.2 (109.8 predicted, +2.1) 1999.12 169.8 84.6 (108.2 predicted, -1.6) 2000.01 158.1 90.2 (108.6 predicted, +0.4) 2000.02 174.1 112.3 (112.0 predicted, +3.4) 2000.03 208.2 138.2 (115.8 predicted, +3.8) 2000.04 184.2 125.3 2000.05 139.6 (1) 35.2 (2) 1) Running average based on the daily 20:00 UTC 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 in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]