Subject: SOHO/LASCO Partial HALO CME 101111

UCMEO 93001 01113 1833/
01111 61648 82318 2961/ 215// 113// 30452
01111 61604 81750 20822 11123 1212/
99999

PLAIN

SOHO/LASCO observed an asymmetric partial HALO CME on November 11, 2010.  
Event is first seen in C2 at 16:48 UT as a faint but defined loop over the South pole.
Material expands, a fainter loop system extends over the east hemisphere from position
angle 296 - 215 degrees totaling 279 degrees wide. 
The event is seen in first frame of C3 at 17:30 UT and tracked out to 23:18 UT 
at 16.5 Rsun where the event dissipates.

Time/height measurements are made at 2 positions,  The event consists of 2 defining
systems which are associated. The first measure (a) is marked to 10 points in C2 with 
speeds of 521.0 km/sec, the event decelerates in C3, marked at 15 points and calculated 
to velocities averaging thru both fields to 451.5 Km/sec at position angle 144 degrees.
The first measure (a) is the brighter of the leading edge (LE) loops.  The second measure (b)
was marked at 5 points in C2 at 791.8 km/sec at PA 96, decelerates in C3 at 4 points for 
an average speed of 635.6 km/sec at PA 98 degrees. 

GOES claims a C4.3 class xray flare from AR 11123 at 15:54-16:16 UT.
SDO AIA 193A shows a flare of AR 11123 beginning at 16:04 - 16:21 UT. In AIA 304 the 
flare of AR 11123 is seen along with the trigger of the filament lying south of the 
active region. The filament begins eruption approximately 16:04 UT and seems to end 
about 17:50 UT. The brighter edge in the South in C2 appears to be associated directly
with the filament eruption as the material over the east an in the North is burst
directed by the flare.  The cooperation of these events are most probably the cause of the
event seen in LASCO.

The observation of this event is considered 'fair'. This CME is determined a FRONTSIDED event.

Images and movies and time/height information for this event is available on the web at:

http://umbra.nascom.nasa.gov/lasco/observations/halo/2010/101111/

Best regards,

Kevin Schenk
SOHO Mission
EIT and LASCO Operations
NASA-Goddard Space Flight Center, USA

BT
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