:Issued: 2011 Oct 31 2039 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 565 from 2011 Oct 24
SOLAR ACTIVITY
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Solar activity was low to moderate during this week. The Sun only produced
small C-flares, most of them occurring in NOAA AR 11324, 11330 or 11333.
The proton flux observed by GOES (>10 MeV) reached the proton event
threshold for a brief period around 15h UT on October 23. This increase
was linked to the M1.3 flare of October 22.
GEOMAGNETIC ACTIVITY
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Geomagnetic activity was quiet during this week, except for a magnetic
storm on October 24-25. The ACE spacecraft observed an interplanetary
shock passage on October 24 at 17:48 UT, most likely linked to the arrival
of a CME that occurred on October 22 in association with an eruptive
filament. Solar wind velocities increased from 350 km/s to 525 km/s and the
interplanetary magnetic field increased to above 20 nT, while its Bz
component reached -20 nT a few times. An associated geomagnetic storm
lasted from October 24 around 20h UT to October 25 around 6h UT. It reached
major storm levels from 1h to 4h UT, and even one hour of severe storm
around 2h UT.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Oct 24 /// 084 145 024 B5.4 0 0
2011 Oct 25 /// 077 139 033 B4.8 0 0
2011 Oct 26 /// 072 132 004 B4.3 0 0
2011 Oct 27 /// 058 132 005 B3.4 0 0
2011 Oct 28 /// 067 134 001 B5.0 0 0
2011 Oct 29 /// 059 123 000 B4.3 0 0
2011 Oct 30 /// 066 127 008 B5.0 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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