Subject: SOHO/LASCO HALO CME 120326 BACKSIDED

UCMEO 93001 20327 2000/
20326 72312 80330 0822/ 081// 333// 41387
20326 62236 80255 ///// 11429 1112/
99999

PLAIN

SOHO/LASCO observed a full asymmetric HALO CME on March 26, 2012.  Event is
first seen in C2 at 23:12 UT with a bright loop at over the east limb at 4.1
Rsun at first frame. The event expands to a full halo by 23:26 UT.  
The event continues into the C3 field beginning 23:18 to 03:30 UT leaving
the C3 field at 30 Rsun in the east.

Time/height measurements were marked [20120326a] to 2 points in C2 with speeds 
of 1765.5 Km/sec at position angle 82 degrees. The event is marked to 9 points 
in C3. Speeds average through both fields to 1387.2 Km/sec at PA 75 degrees.  
Acceleration -55.43 m/sec^2.
A second set of measurements were taken on the west flank [20120326b] and marked
at 5 points in C2 with speeds of 731.1 at PA 260 degrees.  The event is marked at
8 points in C3.  Speeds averaged through both fields to 603.2 km/sec at PA 267 degrees.
Acceleration of -5.60 m/sec^2.

SDO/AIA 193 shows rising loops with a cme beginning 22:33 UT over the east limb.
A wave is seen with small amount of the material on the northeast.  Majority of the
wave is to the back of the disk.

STEREO: Beacon data
COR2 B, First seen at 23:25 UT as a symmetric halo with core material over the West
and North. The event expands, leaving the COR2 field at 02:55 UT.
Preliminary time/height measure gives 931.1 km/sec velocity at LE. 
EUVI B, 22:36-23:56 UT shows a flare with cme of AR 11429(?) near disk center with 
wave and dimming which propagates across the face of the disk in EUVI B images.
COR2 A, 3/26 16:54-04:24 UT data gap.  n/a
EUVI A, 3/26 16:45-04:15 UT data gap.  n/a

   
The observation of this event is considered 'GOOD'. This CME is determined a BACKSIDED 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/2012/120326/

Best regards,

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

BT