Solar Terrestrial Activity Report [Image] Last update May 5, 2001 at 05:40 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 4. Solar wind speed ranged between 358 and 417 km/sec, most of the day under the influence of a weak coronal stream. Solar flare activity was low. Solar flux was 175.6, the planetary A index was 9 (3-hour K indices: 1333 2222, Boulder K indices: 1233 2322). Region 9436 rotated off the visible disk. Region 9441 decayed slowly and was quiet. Regions 9442 and 9444 decayed slowly and were quiet, region 9444 was spotless by early evening. Region 9445 was mostly unchanged and is still capable of producing minor M class flares. Region 9447 developed slowly and could be the source of minor M class flares. Region 9448 was quiet and stable, as was region 9449. New region 9450 emerged in the southeast quadrant near the central meridian. New region 9451 rotated into view at the southeast limb. Flares and CMEs A total of 3 C class events were recorded on May 4. Region 9445 produced a C1.4 flare at 10:58 UTC. Region 9447 was the source of a long duration C4.1 event peaking at 15:00 UTC. The background x-ray flux is at the class B6 level. Coronal holes A trans equatorial coronal hole was in a geoeffective position on May 1-3. Forecast The geomagnetic field is expected to be quiet to unsettled on May 5-6 with a possibility of active intervals. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to 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 9436 2001.04.21 1 S08W99 0050 HSX 9440 2001.04.26 N08W86 plage 9441 2001.04.26 10 N06W57 0200 DAO beta-gamma 9442 2001.04.26 1 N27W41 0040 HSX 9443 2001.04.27 S10W70 plage 9444 2001.04.28 1 S11W16 0000 AXX 9445 2001.04.28 37 N25W04 0300 FAI beta-gamma 9446 2001.04.29 S05W88 plage 9447 2001.04.30 26 N12W41 0260 EAI beta-gamma 9448 2001.05.01 5 N20E34 0120 CAO 9449 2001.05.02 1 S17E44 0080 HSX 9450 2001.05.04 3 S03W07 0020 CRO 9451 2001.05.04 1 S22E76 0080 HSX Total number of sunspots: 86 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) 2001.05 177.2 (1) 21.7 (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]