Subject: SOHO/LASCO HALO CME 120313

UCMEO 93001 20313 1930/
20313 61736 91930 3051/ 304// 333// 31898
20313 61709 81824 46117 11429 1112/
99999

PLAIN

SOHO/LASCO observed an asymmetric HALO CME on March 13, 2012.  Event is first
seen in C2 at 17:36 UT as a bright loop at 3.2 Rsun in the first frame.
The event continues into the C3 field beginning 17:56 to 19:30 UT at 22.8 Rsun
in the last frame in C3 before a temporary DSN data gap. Increased proton emission
is seen in the lasco white light images.

Time/height measurements were marked to only 1 point in C2. 
The event is marked to 5 points in C3. Speeds average through both fields
to 1897.8 Km/sec at PA 305 degrees.  Acceleration -1.12 m/sec^2.


SDO/AIA 193 shows a flare of AR 11429 located at [N17,W61] beginning 17:09-18:24 UT.
The event produces a wave and dimming spanning the west hemisphere.

STEREO: Beacon data
COR2 B, First seen at 17:40 UT as it expands to a symmetric halo. 
Preliminary time/height measure gives 1394.4 km/sec velocity at LE. 
EUVI B, 17:26 UT a cme over the north and west in difference images.
COR2 A, data gap beginning 15:54 UT.  n/a
EUVI A, data gap beginning 16:05 UT.  n/a 

NOAA reports a M7.9 Xray flare of AR 11429 17:12-18:25 UT.
An instant increase in proton flux is shown, particles >50 MeV range
at storm level conditions.
   
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/2012/120313/

Best regards,

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

BT