:Issued: 2011 Sep 20 2157 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 559 from 2011 Sep 12
SOLAR ACTIVITY
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Seventeen sunspot groups were reported by Catania during the week, namely (with NOAA AR numbers shown in brackets): 59 (1287), 61, 68 and 69 (together constituting the NOAA AR 1289), 62 (1290), 64 (1288), 65 (no NOAA number), 66 (no NOAA number), 67 (1293), 70 (1294), 71 (1292), 72 (1295), 73 (1298), 74 (1296), 75 (1297), 76 (1291), 77 (1299). Two more sunspot groups (NOAA ARs 1300 and 1301) got Catania numbers only later (78 and 80). This makes it 19 sunspot groups observed during the week. Nine of the groups (Catania numbers 59, 61, 62, 71, 72, 73, 74, 75, 80) produced frequent flaring activity at the C-level. The strongest flares during the week were: C9.9 flare peaking at 20:54 UT on September 12 in Catania sunspot group 72 (NOAA AR 1295), C9.2 flare peaking at 20:51 UT on September 14 in Catania sunspot group 75 (NOAA AR 1297), C7.8 flare peaking at 00:19 UT on September 16 in Catania sunspot group 75 (NOAA AR 1297), C9.3 flare peaking at 11:30 UT on September 16 in Cat!
ania sunspot group 62 (NOAA AR 1290).
On September 14 SOHO/LASCO detected a partial halo CME first visible in the LASCO C2 field of view at 00:00 UT. The angular width of the CME was around 259 degrees, and the plane-of-the sky speed around 460 km/s. STEREO A SECCHI/COR2 beacon data indicated that the CME was Earth-directed and its true radial speed was closer to 500 km/s. Coronal dimmings and a post-eruption arcade detected by SDO/AIA in Catania sunspot groups 61 and 69 (together constituting the NOAA AR 1289) confirm that the CME was frontsided. The CME was accompanied by a long-duration flaring event in the Catania sunspot groups 61 and 69 (NOAA AR 1289) peaking at 23:36 UT on September 13. Note that the corresponding C2.9 flare is attributed by NOAA to the Catania sunspot group 72 (NOAA AR 1295) near the east solar limb, as another flare occurred in this active region nearly simultaneously. The corresponding ICME arrived at the Earth on September 17 (see below).
GEOMAGNETIC ACTIVITY
--------------------
In the beginning of the week, solar wind speed at the Earth was elevated (up to 660 km/s) in the wake of the ICME arrival on September 9-10 and due to the fast flow from an equatorial coronal hole. This resulted mostly in active geomagnetic conditions, with one interval of K = 5 reported by NOAA on September 12 and by Dourbes on September 13. On September 14 the fast solar wind flow finished, and the geomagnetic conditions became quiet.
On September 17, an interplanetary shock wave was detected by ACE (at 02:55 UT) and SOHO (at 03:05 UT). The shock was driven by the ICME corresponding to the halo CME on September 14 (see above). The interplanetary magnetic field magnitude in the post-shock sheath reached 13 nT, with direction alternating between northward and southward. The ICME arrived in the afternoon of September 17, with the southward Bz in its leading part. This resulted in minor geomagnetic storm on September 17 (K index reached 5 as reported by Dourbes and IZMIRAN, and 6 as reported by NOAA.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Sep 12 172 092 124 030 B6.0 0 0
2011 Sep 13 171 095 129 020 B5.3 0 0
2011 Sep 14 178 111 143 006 B5.6 0 0
2011 Sep 15 233 126 141 007 B6.0 0 0
2011 Sep 16 184 125 143 003 B8.0 0 0
2011 Sep 17 /// 111 145 032 B8.2 0 0
2011 Sep 18 /// 094 150 006 B9.2 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
#--------------------------------------------------------------------#
# 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 #
#--------------------------------------------------------------------#
:Product: documentation at http://www.sidc.be/products/bul
#--------------------------------------------------------------------#
# SIDC Weekly bulletin on Solar and Geomagnetic activity #
#--------------------------------------------------------------------#
WEEK 559 from 2011 Sep 12
SOLAR ACTIVITY
--------------
Seventeen sunspot groups were reported by Catania during the week, namely (with NOAA AR numbers shown in brackets): 59 (1287), 61, 68 and 69 (together constituting the NOAA AR 1289), 62 (1290), 64 (1288), 65 (no NOAA number), 66 (no NOAA number), 67 (1293), 70 (1294), 71 (1292), 72 (1295), 73 (1298), 74 (1296), 75 (1297), 76 (1291), 77 (1299). Two more sunspot groups (NOAA ARs 1300 and 1301) got Catania numbers only later (78 and 80). This makes it 19 sunspot groups observed during the week. Nine of the groups (Catania numbers 59, 61, 62, 71, 72, 73, 74, 75, 80) produced frequent flaring activity at the C-level. The strongest flares during the week were: C9.9 flare peaking at 20:54 UT on September 12 in Catania sunspot group 72 (NOAA AR 1295), C9.2 flare peaking at 20:51 UT on September 14 in Catania sunspot group 75 (NOAA AR 1297), C7.8 flare peaking at 00:19 UT on September 16 in Catania sunspot group 75 (NOAA AR 1297), C9.3 flare peaking at 11:30 UT on September 16 in Cat!
ania sunspot group 62 (NOAA AR 1290).
On September 14 SOHO/LASCO detected a partial halo CME first visible in the LASCO C2 field of view at 00:00 UT. The angular width of the CME was around 259 degrees, and the plane-of-the sky speed around 460 km/s. STEREO A SECCHI/COR2 beacon data indicated that the CME was Earth-directed and its true radial speed was closer to 500 km/s. Coronal dimmings and a post-eruption arcade detected by SDO/AIA in Catania sunspot groups 61 and 69 (together constituting the NOAA AR 1289) confirm that the CME was frontsided. The CME was accompanied by a long-duration flaring event in the Catania sunspot groups 61 and 69 (NOAA AR 1289) peaking at 23:36 UT on September 13. Note that the corresponding C2.9 flare is attributed by NOAA to the Catania sunspot group 72 (NOAA AR 1295) near the east solar limb, as another flare occurred in this active region nearly simultaneously. The corresponding ICME arrived at the Earth on September 17 (see below).
GEOMAGNETIC ACTIVITY
--------------------
In the beginning of the week, solar wind speed at the Earth was elevated (up to 660 km/s) in the wake of the ICME arrival on September 9-10 and due to the fast flow from an equatorial coronal hole. This resulted mostly in active geomagnetic conditions, with one interval of K = 5 reported by NOAA on September 12 and by Dourbes on September 13. On September 14 the fast solar wind flow finished, and the geomagnetic conditions became quiet.
On September 17, an interplanetary shock wave was detected by ACE (at 02:55 UT) and SOHO (at 03:05 UT). The shock was driven by the ICME corresponding to the halo CME on September 14 (see above). The interplanetary magnetic field magnitude in the post-shock sheath reached 13 nT, with direction alternating between northward and southward. The ICME arrived in the afternoon of September 17, with the southward Bz in its leading part. This resulted in minor geomagnetic storm on September 17 (K index reached 5 as reported by Dourbes and IZMIRAN, and 6 as reported by NOAA.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Sep 12 172 092 124 030 B6.0 0 0
2011 Sep 13 171 095 129 020 B5.3 0 0
2011 Sep 14 178 111 143 006 B5.6 0 0
2011 Sep 15 233 126 141 007 B6.0 0 0
2011 Sep 16 184 125 143 003 B8.0 0 0
2011 Sep 17 /// 111 145 032 B8.2 0 0
2011 Sep 18 /// 094 150 006 B9.2 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
#--------------------------------------------------------------------#
# 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 #
#--------------------------------------------------------------------#