:Issued: 2011 Nov 29 1413 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 569 from 2011 Nov 21
SOLAR ACTIVITY
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Thirteen sunspot groups were reported by Catania during the week (corresponding NOAA AR number is given in brackets): 46 (1346), 50 (1352), 51 (1354), 52 (1353), 53 (1355), 55 (1357), 57 (no NOAA number), 58 (1356), 59 (1358), 60 (1359), 61 (1360), 62 (1361), and 63 (no NOAA number). The flaring activity during the week was at the low end of the C-level, with the strongest flare being the C4.9 flare peaking at 04:04 UT on November 22 in Catania sunspot group 58 (NOAA AR 1356). A weak partial halo CME was detected by SOHO/LASCO in association with this flare, accompanied by coronal dimmings and a post-eruption arcade detected by SDO/AIA. The CME first appeared in the LASCO C2 field of view at 06:24 UT, with the speed of around 590 km/s and the angular width around 200 degrees. Due to the source region position far from the central meridian (N12E46), this CME was directed mostly to the east and did not arrive at the Earth.
A solar proton event was detected by GOES and ACE starting on November 26. An increase of the proton flux at energies above 10 MeV was detected by GOES starting from around 08:30 UT, and the SEP event threshold was crossed around 11:00 UT. Proton flux at energies above 50 MeV increased as well. The proton event was produced by the full halo CME first detected in the LASCO C2 field of view at 07:00 UT on the same day. Its speed was around 780 km/s. Coronal dimmings, a filament eruption and a post-eruption arcade were detected by SDO/AIA to the west of the Catania sunspot group 52 (NOAA AR 1353) in association with this event. The CME was associated with the double-peaked C-class flare. The C1.2 peak at 07:10 UT at N11W47 was associated with the above-mentioned filament eruption. The C1.5 peak at 08:24 UT located in the Catania sunspot group 55 (NOAA AR 1357) at the north-west limb was not associated with any CME.
The shock wave driven by the ICME corresponding to this halo CME was detected by SOHO/CELIAS at 21:27 UT on November 28. The proton flux was decreasing throughout November 27 and went below the SEP event threshold around 24:00 UT.
Another full halo CME first appeared in the LASCO C2 field of view at 14:00 UT on November 27. STEREO/SECCHI data demonstrate that it was a far side CME and therefore it will not arrive at the Earth.
GEOMAGNETIC ACTIVITY
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During the whole week the Earth was inside a slow solar wind flow and geomagnetic conditions were quiet. On November 23 at 13:53 UT an interplanetary shock was detected by SOHO/CELIAS. Due to low solar wind speed, geomagnetic conditions remained quiet.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Nov 21 /// 081 141 007 B5.1 0 0
2011 Nov 22 /// 091 142 008 B4.8 0 0
2011 Nov 23 167 088 140 007 B4.4 0 0
2011 Nov 24 /// 085 137 012 B3.9 0 0
2011 Nov 25 177 102 135 005 B4.5 0 0
2011 Nov 26 171 088 133 005 B3.9 0 0
2011 Nov 27 /// 080 135 007 B4.0 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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