Subject: SOHO/LASCO Partial HALO CME 110324

UCMEO 93001 10325 1830/
10324 61248 81730 2851/ 103// 313// 30449
10324 61203 81214 24515 11176 1112/
99999

PLAIN

SOHO/LASCO observed a Partial HALO CME on March 24, 2011.  Event is first seen in        
C2 at 12:48 UT as a faint expanding loop centered at PA 55 degrees followed by an
interior loop with cavity.  The front expands with extensions PA 285-103 degrees 
for a total coverage of 179 degrees over the Northern hemisphere. The event continues
into the C3 field beginning 13:42 to 17:30 UT out to approximately 14.8 Rsun.

Time/height measurements were marked to 6 points in C2 with speeds of 587.1 Km/sec 
at position angle 62 degrees. The event is marked to 8 points in C3 where it 
slightly decelerates.  Speeds average through both fields to 449.3 Km/sec at 
PA 60 degrees.  Acceleration -19.17 m/sec^s.


SDO/AIA 193 shows a flare of AR 11176 located at [S15, E45] on disk beginning
12:03-12:14 UT with a dimming to the North, NW projection and a faint wave.         
NOAA reports an impulsive M1.0 Xray flare of AR 11176 beginning at 12:01-12:11 UT.
STEREO COR2 B sees an expanding burst beginning 13:09 UT in it's NE limb as
does EUVI B 195 shows AR11176 in it's SW quadrant with a flare at 12:05 UT in the 
beacon data. 
This is most probably the cause of the HALO event seen in LASCO.
[NOTE:] EIVI A 195 does show small activity of AR 11174? in it's NW field at 12:35 UT, this could 
possibly be part of the faint material extensions seen in lasco in the NW. 
   
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/2011/110324/

Best regards,

Kevin Schenk
Solar Heliospheric Observatory
EIT and LASCO Operations
NASA-Goddard Space Flight Center, USA

BT