:Issued: 2010 Feb 02 1109 UTC
:Product: documentation at http://www.sidc.be/products/bul
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# SIDC Weekly bulletin on Solar and Geomagnetic activity #
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WEEK 474 from 2010 Jan 25
SOLAR ACTIVITY
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Three sunspot groups were recorded on the solar disk during the week: Catania numbers 37, 38 and 39 (NOAA ARs 1041, 1042 and 1043 respectively). Catania sunspot group 38 was active in the beginning of the week. It produced several B-class flares on January 26-27, the strongest one being the B6.7 flare on January 26. Late on January 27 it disappeared behind the west limb. Catania sunspot group 37 produced several B-class flares on January 27-28, the strongest one being the B4.0 flare on January 28. Catania sunspot group 39 emerged rapidly on January 30 and produced several B-class flares on January 30-31, including the B4.8 flare on January 31.
GEOMAGNETIC ACTIVITY
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During the most of the week, the Earth was inside a slow solar wind stream (speed below 400 km/s). The geomagnetic conditions were quiet. On January 30-31 a slightly faster solar wind stream arrived (peak speed around 450 km/s), accompanied by the interplanetary sector boundary crossing early on January 31. The interplanetary magnetic field north-south component in the stream interaction region was fluctuating and not very strong (down to -5 nT only). The geomagnetic conditions remained quiet.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2010 Jan 25 041 025 81 004 A7.1 0 0
2010 Jan 26 /// 015 80 006 A6.4 0 0
2010 Jan 27 /// 008 78 001 A6.3 0 0
2010 Jan 28 017 008 76 006 A6.2 0 0
2010 Jan 29 011 008 73 002 A2.6 0 0
2010 Jan 30 /// 000 75 006 A2.4 0 0
2010 Jan 31 /// 011 75 005 A3.3 0 0
# RC : Sunspot index (Wolf Number) from Catania Observatory (Italy)
# EISN : Estimated International Sunspot Number
# 10cm : 10.7 cm radioflux (DRAO, Canada)
# Ak : Ak Index Wingst (Germany)
# BKG : Background GOES X-ray level (NOAA, USA)
# M,X : Number of X-ray flares in M and X class, see below (NOAA, USA)
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NOTICEABLE EVENTS
DAY BEGIN MAX END LOC XRAY OP TENCM TYPE Cat NOAA NOTE
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