:Issued: 2011 Apr 26 0737 UTC
:Product: documentation at http://www.sidc.be/products/bul
#--------------------------------------------------------------------#
# SIDC Weekly bulletin on Solar and Geomagnetic activity #
#--------------------------------------------------------------------#
WEEK 538 from 2011 Apr 18
SOLAR ACTIVITY
-------------
During the past week, 7 different NOAA active regions were visible on the solar disk. In the beginning of the week NOAA AR 1193 (Catania 55) with a beta-gamma configuration was responsible for most of the solar activity, producing several C-flares. However, when NOAA AR 1195 (Catania 58) turned over the east limb on april 19th, it took over this role. Cat 58 was the source of a large number of C-flare throughout the week, in addition to 2 M-flares on April 22. (an M1.8 flare preaching at 04h45 and an M1.2 flare around 15h53). Afterwards solar activity returned to quiet levels with the X-ray background flux at B-level.
The STEREO/COR2 and LASCO chronograph images did not show any clear CME linked to any of these flares. However, Cactus detected a CME at 04h12 UT on the morning of April 18, originating from AR 1190. As this region was located on the west limb during the eruption, this CME was not directed towards the earth. SDO/AIA 304 and STEREO-B/COR2 images showed a filament eruption that took place on April 19. Cactus detected the associated CME in LASCO at 22h24 in the NE with a speed of 500 km/s. The CME was directed mostly northwards, and did not reach the Earth. Finally, LASCO also observed a CME at 05h24 on april 21 morning in the NE quadrant, most probably originating from the AR just behind the limb there.
GEOMAGNETIC ACTIVITY
-------------------
A discontinuity was observed in the solar wind around 06h00 UT on April 18. It was most probably linked to the arrival of the CME that was observed late on april 15th and caused one period of unsettled conditions (Kp=4). Geomagnetic conditions became active in the morning of April 20, due to the arrival of a fast coronal wind stream (starting the day before around 20h). The solar wind speed increased up to 550 km/s. The local K index in Dourbes reached a maximum of K=4 (and Kp=5 for one period).
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Apr 18 068 043 111 008 B3.8 0 0
2011 Apr 19 078 045 111 005 B4.2 0 0
2011 Apr 20 107 047 117 018 B4.1 0 0
2011 Apr 21 088 054 113 006 B4.5 0 0
2011 Apr 22 /// 055 115 006 B8.4 2 0
2011 Apr 23 /// 051 119 004 B3.7 0 0
2011 Apr 24 /// 041 117 008 B3.8 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
22 0435 0457 0514 S18E43 M1.8 SN 58 1195
22 1547 1553 1611 S18E35 M1.2 1N 58 1195
#--------------------------------------------------------------------#
# 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 538 from 2011 Apr 18
SOLAR ACTIVITY
-------------
During the past week, 7 different NOAA active regions were visible on the solar disk. In the beginning of the week NOAA AR 1193 (Catania 55) with a beta-gamma configuration was responsible for most of the solar activity, producing several C-flares. However, when NOAA AR 1195 (Catania 58) turned over the east limb on april 19th, it took over this role. Cat 58 was the source of a large number of C-flare throughout the week, in addition to 2 M-flares on April 22. (an M1.8 flare preaching at 04h45 and an M1.2 flare around 15h53). Afterwards solar activity returned to quiet levels with the X-ray background flux at B-level.
The STEREO/COR2 and LASCO chronograph images did not show any clear CME linked to any of these flares. However, Cactus detected a CME at 04h12 UT on the morning of April 18, originating from AR 1190. As this region was located on the west limb during the eruption, this CME was not directed towards the earth. SDO/AIA 304 and STEREO-B/COR2 images showed a filament eruption that took place on April 19. Cactus detected the associated CME in LASCO at 22h24 in the NE with a speed of 500 km/s. The CME was directed mostly northwards, and did not reach the Earth. Finally, LASCO also observed a CME at 05h24 on april 21 morning in the NE quadrant, most probably originating from the AR just behind the limb there.
GEOMAGNETIC ACTIVITY
-------------------
A discontinuity was observed in the solar wind around 06h00 UT on April 18. It was most probably linked to the arrival of the CME that was observed late on april 15th and caused one period of unsettled conditions (Kp=4). Geomagnetic conditions became active in the morning of April 20, due to the arrival of a fast coronal wind stream (starting the day before around 20h). The solar wind speed increased up to 550 km/s. The local K index in Dourbes reached a maximum of K=4 (and Kp=5 for one period).
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2011 Apr 18 068 043 111 008 B3.8 0 0
2011 Apr 19 078 045 111 005 B4.2 0 0
2011 Apr 20 107 047 117 018 B4.1 0 0
2011 Apr 21 088 054 113 006 B4.5 0 0
2011 Apr 22 /// 055 115 006 B8.4 2 0
2011 Apr 23 /// 051 119 004 B3.7 0 0
2011 Apr 24 /// 041 117 008 B3.8 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
22 0435 0457 0514 S18E43 M1.8 SN 58 1195
22 1547 1553 1611 S18E35 M1.2 1N 58 1195
#--------------------------------------------------------------------#
# 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 #
#--------------------------------------------------------------------#