:Issued: 2011 Dec 13 0756 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 571 from 2011 Dec 05
SOLAR ACTIVITY
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Solar activity was low with only a few C flares (GOES X-ray
background at B level). There were up to 10 active regions
present on the solar disk early in the week. The main active
region was Catania#66 (NOAA 11363), of type Dki with a Beta-
Gamma magnetic configuration. This region decayed over the
second half of the week.
No low-latitude coronal hole was seen on the solar disk. The only
noteworthy event was the eruption of a large filament in the NE
quadrant of the solar disk on Dec.11, around 6:00UT.
GEOMAGNETIC ACTIVITY
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During the first 4 days of the week, the solar wind speed
remained below 400 km/s with a weak interplanetary magnetic
field. This led to very quiet geomagnetic conditions.
On Dec.9, the entrance in a new heliospheric sector brought a
slight increase of the interplanetary magnetic field and of
solar wind speed (450 km/s). This induced unsettled conditions
during the last 3 days of the week.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Dec 05 226 098 158 003 B5.2 0 0
2011 Dec 06 /// 102 151 001 B4.7 0 0
2011 Dec 07 /// 087 149 001 B4.5 0 0
2011 Dec 08 /// 109 145 003 B4.4 0 0
2011 Dec 09 /// 078 144 004 B3.8 0 0
2011 Dec 10 /// 070 140 012 B4.2 0 0
2011 Dec 11 /// 065 134 008 B4.7 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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# Solar Influences Data analysis Center - RWC Belgium #
# Royal Observatory of Belgium #
# Fax : 32 (0) 2 373 0 224 #
# Tel.: 32 (0) 2 373 0 491 #
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