ubject: SOHO/LASCO HALO CME 120310 UCMEO 93001 20311 1730/ 20310 61805 82218 3091/ 308// 333// 41037 20310 61718 81836 42417 11429 1112/ 99999 PLAIN SOHO/LASCO observed a HALO CME on March 10, 2012. Event is first seen in C2 at 18:05 UT as a symmetric halo with core material to the north and west. The event continues into the C3 field beginning 18:18 to 22:18 UT leaving the C3 field at 30 Rsun in the north. Time/height measurements were marked [20120310] to 5 points in C2 with speeds of 1010.6 Km/sec at position angle 309 degrees. The event is marked to 11 points in C3. Speeds average through both fields to 1037.1 Km/sec at PA 309 degrees. Acceleration -10.97 m/sec^2. A second set of measurements were taken over the east [20120310b]. C2 marked at 3 points with speeds of 1190.4 km/sec at pa 76 degrees. C3 marked at 6 points. Averaged speeds through both fields 999.4 km/sec at pa 77. Acceleration of -9.83 m/sec^2. SDO/AIA 193 shows a flare of AR 11429 located at [N17,W24] beginning 17:18-18:36 UT. The event produces a wave and dimming which propagates the front of the disk. STEREO: Beacon data COR2 B, First seen at 17:55 UT with an expanding loop CME with cavity and core over the west hemisphere. Preliminary time/height measure gives 1507.5 km/sec velocity at LE. EUVI B, 17:46-18:24 UT a cme over the west limb. COR2 A, 17:39-18:24 UT data gap. At 18:24 UT first frame with LE of event at 8.3 Rsun. Preliminary time/height measure gives 1677.5 km/sec velocity at LE. EUVI A, 17:18-18:35 UT Flare of AR 11429 on NE limb with wave over the east hemisphere. NOAA reports a M8.4 Xray flare of AR 11429 17:15-18:30 UT. The observation of this event is considered 'GOOD'. 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/2012/120310/ Best regards, Kevin Schenk Solar Heliospheric Observatory EIT and LASCO Operations NASA-Goddard Space Flight Center, USA BT