Solar Terrestrial Activity Report [Image] Last update May 1, 2001 at 04:40 UT. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update April 2, 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 to unsettled on April 30. Solar wind speed ranged between 402 and 589 km/sec. Solar flare activity was low. Solar flux was 187.8, the planetary A index was 5 (3-hour K indices: 1000 1331, Boulder K indices: 1101 1210). Region 9433 is rotating off the visible disk, only the trailing spots are visible. The region has simplified but may be capable of producing an M class flare while at the limb. Region 9436 was quiet and stable. Region 9437 decayed further and was spotless by late evening. 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 further and has M class flare potential. Region 9446 decayed and was spotless by late evening. New region 9447 emerged in the northeast quadrant, the region is already spotless. Flares and CMEs A total of 8 C class events were recorded on April 30. Region 9433 produced a C2.6 flare at 02:38 and a C1.6 flare at 11:57 UT. Region 9445 generated a C5.1 flare at 07:21, a C3.6 flare at 10:23, a C1.9 flare at 13:15 and a C2.5 flare at 15:22 UT. The background x-ray flux is at the class B7 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 will rotate into a geoeffective position on May 1-2. Forecast The geomagnetic field is expected to be quiet to unsettled on May 1 and quiet to active on May 2. 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 region numbered sunspots at Area Classification Comment midnight 9433 2001.04.18 22 N17W74 0440 FAI beta-gamma 9436 2001.04.21 1 S10W46 0130 HSX 9437 2001.04.21 3 N09W45 0020 AXX now spotless 9438 2001.04.24 S13W56 plage 9440 2001.04.26 N08W34 plage 9441 2001.04.26 29 N07W04 0240 EAO 9442 2001.04.26 1 N28E09 0050 HSX 9443 2001.04.27 S10W18 plage 9444 2001.04.28 4 S11E38 0020 BXO 9445 2001.04.28 21 N24E48 0330 EAO beta-gamma 9446 2001.04.29 4 S05W36 0010 BXO now spotless 9447 2001.04.30 3 N12E15 0010 BXO now spotless Total number of sunspots: 88 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.01 158.1 90.1 112.9 (+1.8) 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 (115.4 predicted, -0.8) 2000.11 178.8 106.5 (114.2 predicted, -1.2) 2000.12 173.6 104.5 (111.7 predicted, -2.5) 2001.01 166.6 95.7 (108.0 predicted, -3.7) 2001.02 146.6 80.1 (103.5 predicted, -4.5) 2001.03 177.7 114.2 (100.0 predicted, -3.5) 2001.04 177.7 (1) 163.6 (2) (98.8 predicted, -1.2) 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]