Solar Terrestrial Activity Report [Image] Last update April 27, 2002 at 01:10 UTC. [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, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update April 13, 2002)] Recent development The geomagnetic field was quiet on April 26. Solar wind speed ranged between 352 and 451 km/sec. Solar flare activity was low. Solar flux was 162.6 (the lowest solar flux recorded at 20h UTC since August 22, 2001), the planetary A index was 6 (3-hour K indices: 2112 2222, Boulder K indices: 1111 1112). Region 9912 decayed slowly and will rotate over the northwest limb today. Region 9913 decayed further and had only a single small spot left by the end of the day. Region 9914 decayed slowly and quietly. Region 9915 developed slowly and was quiet. There is a minor chance of a small M class flare from this region. Region 9916 decayed further and had lost most of its trailing spots by the end of the day. Region 9919 decayed slowly. The trailing spots developed slowly but do not actually belong to this region, it is almost incredible that SEC/NOAA hasn't yet managed to separate these two regions. Region 9922 decayed and was spotless by the end of the day. Region 9923 decayed quickly and had only a couple of small spots left by midnight, the region could become spotless on April 27. Region 9924 decayed and had single small spot left at the end of the day, the region will likely become spotless on April 27. Region 9925 decayed and was spotless by late afternoon. A new small region emerged south of region 9924 but hasn't yet been numbered by SEC/NOAA. Flares and CMEs A total of 6 C class events were recorded on April 26, none of the flares were optically correlated. A large filament in the southwest quadrant erupted and produced a CME. The CME was first visible in LASCO C3 images at 20:42 UTC but does not appear to be geoeffective. The background x-ray flux is at the class B7 level. Coronal holes A recurrent trans equatorial coronal hole was in a geoeffective position on April 24-25. This coronal hole is smaller than it has been during the last few rotations and decreased further in size after rotating over the central meridian. A small coronal hole in the northern hemisphere will rotate into a geoeffective position on April 27. Another, larger, coronal hole in the southern hemisphere will become geoeffective on April 28-29. Forecast The geomagnetic field is expected to be quiet to active April 27 to May 2 due to coronal hole effects. 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 Location region numbered no. at Area Classification Comment sunspots midnight 9911 2002.04.18 S13W82 plage 9912 2002.04.18 7 N11W78 0130 CAO 9913 2002.04.19 6 S15W72 0040 CRO 9914 2002.04.19 8 N04W25 0260 DSO 9915 2002.04.21 12 N11W12 0190 DAO 9916 2002.04.21 7 S16E07 0030 CSO 9917 2002.04.22 S30W07 plage 9918 2002.04.22 N06W52 plage classification wrong, 9919 2002.04.22 6 N12E33 0190 ESO actually two separate regions 9920 2002.04.23 S24W41 plage 9921 2002.04.23 N12E02 plage 9922 2002.04.23 3 N22E13 0020 BXO now spotless 9923 2002.04.24 7 S03W60 0040 CSO 9924 2002.04.24 1 S15W36 0010 HRX 9925 2002.04.24 5 S14W49 0020 CRO now spotless Total number of sunspots: 62 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 2001.02 146.6 80.6 104.0 (-4.7) 2001.03 177.7 113.5 104.8 (+0.8) 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 (113.3 predicted, -0.8) 2001.11 210.6 106.5 (112.7 predicted, -0.6) 2001.12 235.1 132.2 (109.3 predicted, -3.4) 2002.01 226.6 113.9 (106.0 predicted, -3.3) 2002.02 205.0 108.0 (104.6 predicted, -1.4) 2002.03 179.5 98.1 (100.4 predicted, -4.2) 2002.04 195.6 (1) 177.3 (2) (94.5 predicted, -5.9) 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]