Solar Terrestrial Activity Report [Image] Last update May 17, 2001 at 03:55 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 16. Solar wind speed ranged between 386 and 548 km/sec. Solar flare activity was moderate. Solar flux was 137.8, the planetary A index was 12 (3-hour K indices: 3333 2322, Boulder K indices: 2333 1302). Region 9451 was quiet and stable, the region is rotating off the visible disk. Region 9454 was mostly unchanged and quiet. Region 9455 decayed in the trailing spots section but still has some mixing of polarities in the intermediate section. Further minor M class flares are possible. Region 9456 was quiet and decayed slowly. Region 9458 was quiet and stable. Region 9461 was mostly quiet and stable. Flares and CMEs A total of 7 C and 1 M class events were recorded on May 16. Region 9455 produced a C4.2 flare at 06:34, an impulsive M1.3 flare at 10:42 and a C1.5 flare at 18:40 UTC. Region 9461 generated a C1.1 flare at 08:39 UTC. Region 9458 was the source of a C2.7 flare at 15:50 UTC (with an associated weak type II sweep), while region 9454 managed a C2.3 flare at 23:49 UTC. The background x-ray flux is at the class B5 level. Coronal holes What appears to be a small coronal hole was in a geoeffective position on May 15 and could cause a few unsettled to active intervals on May 18. Forecast The geomagnetic field is expected to be quiet to unsettled on May 17-18 with the chance of a few active intervals on May 18 should a coronal stream arrive. 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 9451 2001.05.04 1 S20W81 0110 HAX 9452 2001.05.07 S10W50 plage 9454 2001.05.10 22 N13W08 0220 EAO beta-gamma 9455 2001.05.11 28 S17W52 0140 FAI beta-gamma 9456 2001.05.12 5 N06W60 0090 DAO 9457 2001.05.13 S21W33 plage 9458 2001.05.14 5 S12W72 0030 DAO 9459 2001.05.14 N26W37 plage 9460 2001.05.14 S24E35 plage 9461 2001.05.15 4 N16E63 0090 DAO Total number of sunspots: 65 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) 2001.05 148.5 (1) 67.4 (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]