Solar Terrestrial Activity Report [Image] Last update May 2, 2001 at 04:25 UT. [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 April 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2001)] [Historical solar and geomagnetic data charts 1954-2000 (last update April 8, 2001)] Recent development The geomagnetic field was quiet on May 1. Solar wind speed ranged between 370 and 512 km/sec. Solar flare activity was moderate. Solar flux was 184.5 (the measurement at 17h UTC was used as the 20h UTC value was enhanced due to flare activity), the planetary A index was 4 (3-hour K indices: 1011 2222, Boulder K indices: 1011 2111). Region 9433 will complete its rotation over the west limb early today. The region could produce isolated M class flares from behind the limb today and tomorrow. Region 9436 was quiet and stable. Region 9441 developed slowly and was quiet. Occasional minor M class flares are possible. Regions 9442 and 9444 were quiet and stable. Region 9445 developed slowly and has M class flare potential. Region 9447, having been spotless for almost a day, reemerged with several spots. New region 9448 rotated into view at the northeast limb. Flares and CMEs A total of 5 C and 1 M class events were recorded on May 1. Region 9441 produced a C2.3 flare at 10:04, a C2.2 flare at 15:15 and a C4.2 flare at 17:35 UTC. Region 9445 generated a C2.0 flare at 16:56 UTC. Region 9433 was the source of a C1.7 flare at 14:41 and an M2.4 long duration event peaking at 19:17 UT. The background x-ray flux is at the class B9 level. Coronal holes An isolated coronal hole in the northern hemisphere was likely in a geoeffective position on April 29. A trans equatorial coronal hole was in a geoeffective position on May 1-2. Forecast The geomagnetic field is expected to be quiet to active on May 2 and quiet to unsettled on May 3. A coronal stream will arrive on May 4 and will likely cause unsettled to minor storm conditions. 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 9433 2001.04.18 7 N19W82 0300 DKI beta-gamma 9436 2001.04.21 1 S11W59 0130 HSX 9437 2001.04.21 N09W58 plage 9438 2001.04.24 S13W69 plage 9440 2001.04.26 N08W47 plage 9441 2001.04.26 25 N06W16 0250 ESI 9442 2001.04.26 4 N29W05 0060 CSO 9443 2001.04.27 S10W31 plage 9444 2001.04.28 3 S09E24 0020 BXO 9445 2001.04.28 28 N26E37 0390 FAI beta-gamma 9446 2001.04.29 S05W49 plage 9447 2001.04.30 3 N12E01 0010 CRO 9448 2001.05.01 1 N22E73 0070 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) 2000.07 202.3 170.1 119.8 (+1.1) 2000.08 163.0 130.5 118.6 (-1.2) 2000.09 182.1 109.7 116.2 (-2.4) 2000.10 167.4 100.1 114.5 (-1.7) 2000.11 178.8 106.5 (112.5 predicted, -2.0) 2000.12 173.6 104.5 (109.9 predicted, -2.6) 2001.01 166.6 95.7 (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) 2001.05 184.5 (1) 4.9 (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]