Solar Terrestrial Activity Report [Image] Last update May 24, 2001 at 05:10 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 active on May 23. Solar wind speed ranged between 303 and 448 km/sec under the influence of a fairly benign coronal stream. Solar flare activity was low. Solar flux was 158.7, the planetary A index was 11 (3-hour K indices: 3222 3433, Boulder K indices: 3323 3432). Region 9461 was quiet and stable, as was region 9462. Region 9463 developed fairly quickly with the leading spot penumbra becoming very large. The region is fairly simple without significant intermixing of the magnetic polarities. Should any magnetic complexity emerge the region will become capable of producing major flares. Regions 9464 and 9465 were quiet and stable. Region 9466 decayed early in the day, then began to develop and is now capable of producing C flares. Region 9467 was quiet and stable. Region 9468 developed at a moderate pace and could soon become capable of producing minor M class flares. Region 9469 decayed slowly and rotated off the visible disk early on May 24. Region 9470 decayed and was spotless by late evening. New region 9471 emerged in the southern hemisphere near the central meridian. New region 9472 rotated into view at the northeast limb. Flares and CMEs A total of 5 C class events were recorded on May 23. Region 9468 produced a C1.2 flare at 12:52 and a C1.0 flare at 14:28 UTC. The background x-ray flux is at the class B4 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on May 24-25 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 9460 2001.05.14 S24W56 plage 9461 2001.05.15 5 N22W31 0040 DAO 9462 2001.05.17 3 N19W03 0080 CSO 9463 2001.05.18 33 N07E04 0720 EKI 9464 2001.05.19 3 S09E11 0010 BXO 9465 2001.05.20 5 S10E19 0010 BXO 9466 2001.05.21 7 S04E14 0020 AXX 9467 2001.05.21 1 S07E29 0080 HSX 9468 2001.05.21 10 N05E39 0150 CAO 9469 2001.05.22 2 N07W83 0050 HAX 9470 2001.05.22 1 S16W32 0000 AXX 9471 2001.05.23 1 S13W02 0000 AXX 9472 2001.05.23 1 N12E61 0050 HSX Total number of sunspots: 72 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) 2001.05 148.0 (1) 96.6 (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]