Subject: SOHO/LASCO HALO CME 121123b BACKSIDED UCMEO 93001 21124 1730/ 21123 62324 80411 3172/ 316// 323// 31278 21123 62256 82336 ///// ///// 1112/ 99999 PLAIN SOHO/LASCO observed a second HALO CME (B) on November 23, 2012. Event is first seen in C2 at 23:24 UT as a loop surfacing over the Northwest limb with cavity and core. The event expands to a full asymmetric halo CME by 00:06 UT. The event continues into the C3 field beginning 23:54 to 04:18 UT leaving the C3 field at 30 Rsun in the Northwest. Time/height measurements were marked to 3 points in C2 with speeds of 1433.2 Km/sec at position angle 317 degrees. The event is marked to 7 points in C3. Speeds average through both fields to 1278.4 Km/sec at PA 317 degrees. Acceleration -64.97 m/sec^2. SDO/AIA : CME is seen over the NW limb in difference images 23:00-23:42 UT. STEREO: Beacon data COR2 A, 22:24-04:39 UT data gap. n/a EUVI A 195, n/a COR2 B, 00:25 UT in progress at first frame. A partial halo over East Preliminary time/height measure gives 1250.5 km/sec velocity at LE. EUVI A 195, shows a flare with CME on limb in NE 22:56-22:36 UT with wave. The observation of this event is considered 'FAIR'. 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/2012/121123b Best regards, Kevin Schenk Solar Heliospheric Observatory EIT and LASCO Operations NASA-Goddard Space Flight Center, USA BT