Solar Terrestrial Activity Report [Image] Last update August 28, 2000 at 06:10 UTC. Minor update posted at 09:02 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update August 4, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update August 4, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update August 4, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update August 10, 2000)] Recent development The geomagnetic field was quiet to unsettled on August 27. Solar wind speed ranged between 346 and 454 km/sec. Solar flare activity was low. Solar flux was 150.1, the planetary A index was 9 (3-hour K indices: 2211 3323, Boulder K indices: 2110 3323). Region 9138 was quiet and stable. Region 9139 decayed further and was quiet, the region will rotate off the visible disk on August 29. Region 9140 developed slowly and was mostly quiet. Region 9142 was quiet and stable. Region 9143 developed slowly and could produce C and occasional minor M class flares. Region 9144 developed slowly and has C and minor M class flaring potential. New region 9145 rotated into view at the southeast limb. New region 9146 emerged near the southeast limb. A very interesting region is currently at or just behind the northeast limb. It appears to be very active and is probably capable of M class flaring. Comment added at 09:02 UTC on August 28: What appears to be a coronal stream has been in progress since 06:10 UTC. Solar wind speed has increased gradually since then and is currently near 550 km/sec. The source of the coronal stream could be a fairly narrow and long coronal hole which begins in the southwest quadrant and stretches in an ENE direction into the northeast quadrant. Unsettled to active conditions will likely be observed for the remainder of the day. Flares and CMEs A total of 8 C class events were recorded on August 27. Region 9144 produced a C1.1 flare at 00:32 UTC. Region 9143 generated a C1.1 flare at 11:02 and a C6.9 flare at 17:40 UTC. Region 9140 was the source of a C1.0 flare at 12:08 UTC. August 26: A filament eruption was observed in the southeast quadrant 10-15 degrees east of the central meridian starting at 11:25 UTC. No obvious CME was observed. The background x-ray flux is at the class B7 level. Coronal holes A coronal hole in the northern hemisphere will rotate into a geoeffective position on August 27-28. Forecast The geomagnetic field is expected to be quiet to unsettled August 28-29. On August 28 there is a possibility of minor geomagnetic effects (causing isolated unsettled to active intervals) from a partial halo CME observed on August 25. A coronal stream could cause unsettled to active conditions on August 30-31. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 no. Location at region numbered sunspots midnight Area Classification Comment 9137 20000819 N24W58 plage 9138 20000819 1 S29W37 0040 HSX 9139 20000820 1 S09W73 0100 HSX 9140 20000822 9 N09W01 0060 DSO 9141 20000823 N16W60 plage 9142 20000824 1 N15E33 0040 HSX 9143 20000824 12 S20E33 0290 EAO beta-gamma 9144 20000825 15 N22W12 0210 DAI 9145 20000827 3 S10E60 0040 CRO 9146 20000827 2 S26E51 0010 BXO Total number of sunspots: 44 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.07 165.6 113.5 94.3 (+1.2) 1999.08 170.7 93.7 97.5 (+3.2) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.8 (+5.5) 1999.11 191.5 133.2 110.9 (+3.1) 1999.12 169.8 84.6 111.0 (+0.1) 2000.01 158.1 90.1 112.8 (+1.8) 2000.02 174.1 112.9 (115.7 predicted, +2.9) 2000.03 208.2 138.5 (118.2 predicted, +2.5) 2000.04 184.2 125.3 (120.4 predicted, +2.2) 2000.05 184.9 120.8 (121.2 predicted, +0.8) 2000.06 179.8 124.9 (122.8 predicted, +1.6) 2000.07 202.3 169.1 2000.08 163.1 (1) 142.7 (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]