Solar Terrestrial Activity Report [Image] Last update May 26, 2002 at 03:00 UTC. Minor update posted at 18:57 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 active on May 26. Solar wind speed ranged between 398 and 507 km/sec, increasing at the end of the day as a coronal stream began to influence the field. Solar flare activity was low. Solar flux was 183.1, the planetary A index was 10 (3-hour K indices: 2122 2334, Boulder K indices: 2022 1324). Region 9957 decayed further and was quiet. Region 9958 was quiet and stable. Region 9960 decayed slowly and quietly. Region 9961 decayed quickly and could soon lose all trailing spots. Region 9962 was quiet and stable. Region 9963 lost some spots and developed new spots in other parts of the region. Although the region is fairly simple, both the positive and negative polarity areas are quite strong. Minor M class flares are possible. Region 9965 was quiet and stable. Region 9966 is part of region 9963 and should be deleted. Region 9967 developed a few new spots and was quiet. Region 9968 was spotless all day in all available images. Region 9969 decayed and had only a few spots left by the end of the day. Region 9970 had emerged south of region 9969 on May 25 and was finally numbered by SEC/NOAA. The region developed quickly early in the day, no significant changes were noted after noon. Comment added at 18:57 UTC on May 27: A large filament eruption in the northeast quadrant was first observed in SOHO EIT images at 12:36 UTC. A fast halo CME was observed soon afterwards in LASCO C3 images, with the CME first observed off the northeast limb at 13:42 UTC (at which time the CME had already expanded well past the limb). The CME will likely impact the Earth on May 29 and could cause unsettled to minor storm conditions. Otherwise a fairly strong and fast (solar wind speed has approached 700 km/sec. ACE reports higher speeds but it should be noted that solar wind speed recorded on ACE is usually unreliable when density is near or below 1 particle per cubic centimeter) coronal stream is influencing the magnetosphere. The geomagnetic field has been quiet to minor storm today. Flares and CMEs A total of 8 C class events were recorded on May 26. Region 9963 produced a C1.1 flare at 02:44 UTC. Region 9961 generated a C4.4 flare at 13:56 UTC. Region 9969 was the source of a C1.7 flare at 15:10 UTC. The background x-ray flux is at the class B7 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to active on May 27-28 due to a coronal stream and quiet to unsettled on May 29. 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 S22W77 plage 9955 2002.05.15 S13W76 plage 9957 2002.05.16 22 N10W58 0280 EAI beta-gamma area too large 9958 2002.05.17 1 N04W71 0040 HSX 9960 2002.05.18 6 N15W31 0030 DSO 9961 2002.05.19 23 S21W17 0250 EAI beta-gamma 9962 2002.05.20 1 N16W21 0030 HSX 9963 2002.05.20 29 N14W03 0410 EHI 9964 2002.05.22 S14W42 plage 9965 2002.05.22 2 S08E05 0040 HSX region should be 9966 2002.05.23 5 N11W06 0020 CSO deleted, it is part of region 9963 9967 2002.05.23 7 N13E05 0020 CSO 9968 2002.05.24 1 S14E00 0000 AXX actually spotless 9969 2002.05.25 9 N09E55 0100 DAO area too large, spot count too high 9970 2002.05.26 6 N05E54 0180 DAO Total number of sunspots: 112 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) 2002.05 177.4 (1) 170.5 (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]