Solar Terrestrial Activity Report [Image] Last update May 12, 2001 at 05:25 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 1, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update May 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 2, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update April 8, 2001)] Recent development The geomagnetic field was quiet to unsettled on May 11. Solar wind speed ranged between 388 and 460 km/sec. Solar flare activity was low. Solar flux was 136.6, the planetary A index was 9 (3-hour K indices: 3122 2333, Boulder K indices: 2232 1323). Regions 9448, 9449, 9451 and 9452 were mostly quiet and stable, however, both regions 9449 and 9452 are decaying and could become spotless by the end of the day. Region 9454 was mostly quiet and stable but could produce minor M class flares. New region 9455 emerged quickly south of region 9452 and already has a weak magnetic delta configuration. Minor M class flares are possible. A new region emerged in the northeast quadrant near the center of the disk but was not included by SEC/NOAA. Flares and CMEs A total of 4 C class events were recorded on May 11. Region 9455 produced a C1.6 flare at 10:06 and was the likely source of a C3.7 flare at 20:22 UTC. A fairly large filament between regions 9452 and 9451 disappeared near noon. There is no obvious CME in LASCO C3 images related to this disappearance, however, there is still a chance a weak, geoeffective CME may have been produced. The background x-ray flux is at the class B3 level. Coronal holes A large, poorly defined coronal hole (could be just a large area with a weak corona) in the northern hemisphere was in a geoeffective position on May 9-12. If there is any coronal stream from this feature, it is likely to be weak. Forecast The geomagnetic field is expected to be quiet to active on May 12-13 with a chance of minor storm intervals due to a coronal stream. 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 Location region numbered no. at Area Classification Comment sunspots midnight 9448 2001.05.01 1 N21W57 0120 HSX 9449 2001.05.02 2 S16W48 0020 CSO 9451 2001.05.04 7 S22W12 0130 CKO 9452 2001.05.07 1 S09E14 0010 AXX 9453 2001.05.09 S08W54 plage 9454 2001.05.10 13 N13E58 0430 EKO beta-gamma 9455 2001.05.11 12 S18E17 0100 DAO beta-gamma-delta Total number of sunspots: 36 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.02 174.1 112.9 116.8 (+3.9) 2000.03 208.2 138.5 119.9 (+3.1) 2000.04 184.2 125.5 120.8 (+0.9) cycle 23 sunspot max. 2000.05 184.9 121.6 119.0 (-1.8) 2000.06 179.8 124.9 118.7 (-0.3) 2000.07 202.3 170.1 119.7 (+1.0) 2000.08 163.0 130.5 118.6 (-1.1) 2000.09 182.1 109.7 116.2 (-2.4) 2000.10 167.4 99.4 114.5 (-1.7) 2000.11 178.8 106.8 (112.5 predicted, -2.0) 2000.12 173.6 104.5 (109.9 predicted, -2.6) 2001.01 166.6 95.6 (106.2 predicted, -3.7) 2001.02 146.6 80.1 (101.8 predicted, -4.4) 2001.03 177.7 114.2 (98.2 predicted, -3.6) 2001.04 177.7 108.2 (97.0 predicted, -1.2) 2001.05 152.8 (1) 45.9 (2) (96.3 predicted, -0.7) 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. ------------------------------------------------------------------------ Do you know about the survey which will be held this Summer among the listeners of WWV and WWVH? There is information about this survey at 16 minutes past the hour on WWV and at 47 minutes past the hour on WWVH. If you want to participate send an email with your name and address. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]