:Issued: 2011 Oct 11 0745 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 562 from 2011 Oct 03
SOLAR ACTIVITY
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Flaring activity was situated in the C-level. The number of C-flares gradually decreased
in the course of the week.
On Oct 04, a slow CME left the Sun. The source region was situated in the southern part
near the central meridian. The CME was not associated with a C-flare. It was an event
in the high corona. An EUV wave and coronal dimming was visible in SDO/AIA 193.
A halo CME was noticed on Oct 04. The intensity in LASCO images was the strongest in the
north east part. The CME was however back-sided.
GEOMAGNETIC ACTIVITY
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A strong shock passed ACE on Oct 05 around 06:45UT. The shock was followed by a magnetic
cloud with the typical temperature depression. The density was relatively high:
10 particles/cm2. This event was probably a combined arrival of three CME's:
Sept 30, Oct 01, Oct 02.
Each sequent CME was faster. With STEREO A COR2 images we estimated the speed near the Sun
to be 250 km/s, 400 km/s and 500 km/s. A possible scenario is that the second one catch
up with the first one, the third one with the second one leading to a high density cloud.
The magnetic response of the Earth led to unsettled and active conditions on a local level.
On the planetary level the Kp index rose to 5 for two periods.
A weak shock arrived at ACE on Oct 08, between 5 and 6 UT. On Oct 09, a magnetic structure
passed. Although the weak shock and the slow magnetic cloud are separated in time, they
are possibly linked to the CME that left the Sun on Oct 04. Locally, the geomagnetic
magnetic field was disturbed up to active conditions. A shock could be formed because
of the slow background solar wind. Dourbes reported unsettled to active conditions
starting from Oct 08. We had a similar response of the Earth magnetic field on the
planetary level.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Oct 03 134 073 129 005 B3.9 0 0
2011 Oct 04 149 084 130 006 B4.3 0 0
2011 Oct 05 141 066 127 016 B5.6 0 0
2011 Oct 06 110 065 124 007 B4.4 0 0
2011 Oct 07 120 060 122 005 B3.9 0 0
2011 Oct 08 /// 047 118 012 B3.3 0 0
2011 Oct 09 /// 051 121 011 B3.0 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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