Solar Terrestrial Activity Report [Image] Last update May 29, 2002 at 03:40 UTC. Minor update posted at 07:46 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 unsettled on May 28. Solar wind speed ranged between 571 and 729 km/sec under the influence of a high speed coronal stream. Solar flare activity was low. Solar flux was 186.4, the planetary A index was 12 (3-hour K indices: 2333 3333, Boulder K indices: 3322 2333). Region 9957 lost all its southern spots but continued to develop quickly in the northern section. An M class flare is possible while the region is at and just behind the northwest limb. Region 9960 decayed slowly leaving only a single small spot at the end of the day, the region is likely to become spotless later today. Region 9961 decayed further and was quiet. Region 9962 decayed and could become spotless today. Region 9963 lost most of its trailing spots. During the latter half of the day strong development was observed near the main penumbra and by midnight a magnetic delta structure had formed as the eastern edge of the main penumbra and the western edge of an emerging negative polarity spot merged. The flare potential is increasing and if the current development continues major flares will become possible. Additionally there appears to be an emerging negative polarity area just ahead of the main penumbra. Region 9965 was quiet and stable. Region 9966 is still considered to be part of region 9963. Region 9967 decayed and was spotless by late afternoon. Region 9969 was mostly quiet and stable. Region 9970 did not change much and remained quiet. New region 9971 emerged briefly in the northeast quadrant near the central meridian, no spots were observed late in the day. New region 9972 developed further and was finally numbered by SEC/NOAA. New region 9973 rotated into view at the southeast limb. This is a large and complex region which may be capable of producing major flares. The region has at least two magnetic delta structures, one in a leading penumbra in the northwest, another in the large trailing penumbra. Comment added at 07:46 UTC on May 29: Region 9973 was the source of a long duration C8 event peaking at 05:17 UTC. A CME was observed off the southeast limb shortly after the LDE began. Flares and CMEs A total of 11 C class events were recorded on May 28. Region 9957 produced a C3.6 flare at 16:35 UTC. Region 9963 generated a C2.7 flare at 03:49 and a C2.9 flare at 21:56 UTC. Region 9973 was the source of a C2.2 flare at 06:07 and a C2.3 flare at 13:35 UTC. Region 9972 produced a C2.6 flare at 15:50 UTC. A large and fast full halo CME was first observed in LASCO C3 images at 16:42 UTC off the southwest limb. The source of this event was likely an eruption well behind that limb. A long duration C6.2 event peaked just before 03h UTC on May 29, the source appears to have been in region 9957. An impulsive C8.5 flare was superimposed on the LDE at 02:43 UTC. May 27: A filament eruption in the northeast quadrant was first observed in SOHO EIT images at 12:36 UTC and peaked as a long duration C3.7 event at 12:59 UTC. A fast partial 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). There is a possibility that the outer edges of the CME could reach the Earth on May 29 or 30 and cause unsettled to active geomagnetic conditions. The background x-ray flux is at the class C1 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on May 29-30, unsettled to active conditions are possible if the CME observed on May 27 is geoeffective. 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 9957 2002.05.16 10 N12W86 0210 DAO beta-gamma-delta 9960 2002.05.18 1 N14W56 0010 HSX 9961 2002.05.19 6 S22W44 0120 EAO 9962 2002.05.20 1 N15W47 0020 HSX 9963 2002.05.20 22 N14W30 0300 DAI beta-gamma-delta 9964 2002.05.22 S14W72 plage 9965 2002.05.22 3 S07W21 0050 CAO 9966 2002.05.23 1 N11W36 0020 HSX region is part of region 9963 too many spots, 9967 2002.05.23 7 N12W23 0020 CRO region is now spotless 9968 2002.05.24 S14W26 plage 9969 2002.05.25 12 N09E30 0040 DSO 9970 2002.05.26 11 N05E28 0170 DAO 9971 2002.05.28 3 N21E00 0010 BXO now spotless 9972 2002.05.28 6 S21E56 0050 CAO 9973 2002.05.28 5 S16E73 0420 EKI beta-gamma-delta Total number of sunspots: 88 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) 2002.05 178.0 (1) 184.8 (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]