Solar Terrestrial Activity Report [Image] Last update May 25, 2002 at 04:55 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 3, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update May 3, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 3, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update April 13, 2002)] Recent development The geomagnetic field was quiet to slightly unsettled on May 25. Solar wind speed ranged between 397 and 535 km/sec. Solar flare activity was low. Solar flux was 182.6, the planetary A index was 6 (3-hour K indices: 2112 2321, Boulder K indices: 0001 2222). Region 9954 decayed and was spotless by early afternoon. Region 9957 decayed significantly in all parts of the region. A minor M class flare is still possible. Region 9958 was quiet and stable. Region 9960 decayed significantly and lost its magnetic delta structure early in the day. If the region continues decaying at the current rate it will become spotless within a couple of days. Region 9961 decayed, particularly in the trailing and intermediate spot sections. No magnetic delta structures were present by the end of the day. Region 9962 decayed slowly and quietly. Region 9963 decayed slowly with some of the small southern spots disappearing. A minor M class flare is possible. Region 9965 was quiet and stable. Region 9966 is part of region 9963 and should be deleted. Region 9967 decayed slowly and could become spotless later today. Region 9968 decayed and was spotless by midnight. New region 9969 emerged at the northeast limb. In magnetograms it is obvious that the region is actually two narrowly separated regions. Mt.Wilson managed to observe this, SEC/NOAA did not. If the regions continue to develop they could become one region. Flares and CMEs A total of 3 C class events were recorded on May 25. Region 9960 produced a C1.3 flare at 05:47 UTC. Region 9961 was the source of a long duration C1.7 event peaking at 17:21 UTC. A small CME was observed off the south pole and the south west limb after this event. The background x-ray flux is at the class B6 level. Coronal holes A small coronal hole in the southern hemisphere was in a geoeffective position on May 25 and could cause a mild geomagnetic disturbance on May 28. Forecast The geomagnetic field is expected to be quiet to unsettled on May 26-27 and quiet to active on May 28. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to very 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 Location region numbered no. at Area Classification Comment sunspots midnight 9954 2002.05.15 1 S22W64 0010 HSX now spotless 9955 2002.05.15 S13W63 plage 9957 2002.05.16 26 N10W45 0310 EAI beta-gamma 9958 2002.05.17 1 N05W58 0030 HSX 9960 2002.05.18 13 N14W20 0060 DAO too many spots 9961 2002.05.19 24 S21W04 0280 EAI beta-gamma 9962 2002.05.20 1 N16W07 0030 HSX 9963 2002.05.20 27 N14E09 0380 EHO 9964 2002.05.22 S14W29 plage 9965 2002.05.22 2 S08E19 0040 HSX region should be 9966 2002.05.23 1 N10E04 0000 AXX deleted, it is part of region 9963 9967 2002.05.23 1 N14E19 0010 HRX 9968 2002.05.24 1 S14E13 0010 HRX now spotless 9969 2002.05.25 3 N09E67 0040 DSO actually two separate regions! Total number of sunspots: 101 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2001.04 177.7 107.7 107.5 (+2.7) 2001.05 147.1 96.6 108.6 (+1.1) 2001.06 173.0 134.0 109.8 (+1.2) 2001.07 131.3 82.2 111.7 (+1.9) 2001.08 162.9 106.8 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 114.0 (-0.1) 2001.11 210.6 106.5 (114.7 predicted, +0.7) 2001.12 235.1 132.2 (112.5 predicted, -2.2) 2002.01 226.6 113.9 (109.8 predicted, -2.7) 2002.02 205.0 108.0 (108.4 predicted, -1.4) 2002.03 179.5 98.1 (104.2 predicted, -4.2) 2002.04 189.8 120.4 (98.3 predicted, -3.9) 2002.05 177.1 (1) 163.0 (2) (93.8 predicted, -4.5) 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 25-45% 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. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News]