:Issued: 2011 Sep 15 1122 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 558 from 2011 Sep 05
SOLAR ACTIVITY
==========
Solar activity was high during the past week.
NOAA AR 11286 produced two M flares on September 5: an M1.6 peaking at 04:28 UT and an M1.2
peaking at 07:58 UT. The active region was at that time located near the very west limb.
The most productive active region this week was however NOAA AR 11283. It produced several M and
2 X flares. The most relevant flares were the M5.3, September 6, peaking at 02:05 UT and
the X2.1, September 6, peaking at 22:20 UT. Both were associated with a halo CME: NOAA 11283 was
located near the central meridian.
The >= 10 MeV proton level rose after the M5.3 flare, and further increased after the X2.1
flare. They stayed just below the threshold, and slowly decreased to normal values.
GEOMAGNETIC ACTIVITY
===============
Geomagnetic activity was low until September 9.
The M5.3 and X2.1 flares each produced a frontsided halo CME. A shock arrived at Earth
on September 9, 11:50UT. The shock was followed by the plasma cloud. We had active to
major storm conditions from September 9, 12 UT till September 11, 4 UT.
Several other CMEs were associated with the flares from NOAA AR 11283. We
list the date, the flare and the time the CME is first visible in the STEREO A/COR2 coronograph:
September 7, X1.8, 23:09 UT;
September 9, M2.7, 06:09 UT;
September 10, M1.1, 10:09 UT.
On September 10, a frontsided partial halo was detected. It came into view of STEREO A/COR2
at 03:09 UT. This CME was probably associated with a filament eruption.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Sep 05 117 076 119 010 C1.6 2 0
2011 Sep 06 /// 058 112 007 B5.7 1 1
2011 Sep 07 090 049 113 006 B3.8 0 1
2011 Sep 08 079 036 110 /// B3.6 1 0
2011 Sep 09 079 046 112 /// B4.2 2 0
2011 Sep 10 082 052 116 038 B4.7 1 0
2011 Sep 11 /// 059 121 017 B4.8 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
05 0408 0428 0432 M1.6 1286
05 0727 0758 0806 M1.2 1286
06 0135 0150 0205 N14W07 M5.3 1B V/1,III/1,II/3,IV/1 54 1283
06 2212 2220 2224 N14W18 X2.1 2B 740 II/2,III/3,IV/3 54 1283
07 2232 2238 2244 N14W28 X1.8 3B 1300 III/2,II/1,IV/1 54 1283
08 1532 1546 1552 N14W40 M6.7 1N 91 III/1,IV/1 54 1283
09 0601 0611 0617 N16W47 M2.7 1N 62 II/1,III/1 54 1283
09 1239 1249 1256 N13W52 M1.2 1F 54 1283
10 0718 0740 0756 N12W61 M1.1 SN III/1 54 1283
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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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