Subject: SOHO/LASCO HALO CME 120318 BACKSIDED UCMEO 93001 20320 1830/ 20318 60012 80518 2912/ 290// 333// 41219 20317 62325 80050 ///// 11429 1112/ 99999 PLAIN SOHO/LASCO observed a full asymmetric HALO CME on March 18, 2012. Event is first seen in C2 at 00:12 UT with a loop at position angle 291. The event expands to a full halo by 01:36 UT. The event continues into the C3 field beginning 00:42 to 05:18 UT leaving the C3 field at 30 Rsun in the northwest. Time/height measurements were marked to 4 points in C2 with speeds of 862.1 Km/sec at position angle 291 degrees. The event is marked to 9 points in C3. Speeds average through both fields to 1218.6 Km/sec at PA 193 degrees. Acceleration 26.13 m/sec^2. SDO/AIA 193 shows a cme of AR 11434 located at [S22,W27] beginning 20:36-20:57 UT. The event produces a small wave and dimming on the SW quadrant of the disk. This event does not seem to appear in C2. A cme event is seen in AIA 193 23:24-01:21 UT over the NW limb with wave slightly protruding over the limb in the N and NNE. STEREO: Beacon data COR2 A, First seen at 00:39 UT as a symmetric halo at first frame, expands and leaves the COR2 field at 03:54 UT. Preliminary time/height measure gives 1049.9 km/sec velocity at LE. EUVI A, 20:36-21:06 UT a cme on the east limb. Later a flare of AR 11429(?) 23:25-23:50 UT and 23:55-00:50 UT at disk center with wave and dimming across the face of the disk in EUVI A images. COR2 B, 13:40-22:25 UT data gap. At 00:25-03:55 UT an asymmetric (east) halo event. Preliminary time/height measure gives 1007.6 km/sec velocity at LE. EUVI B, 13:46-22:26 UT data gap. 23:26-0116 UT cme seen over east limb 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/2012/120318/ Best regards, Kevin Schenk Solar Heliospheric Observatory EIT and LASCO Operations NASA-Goddard Space Flight Center, USA BT