Subject: SOHO/LASCO Partial HALO CME 110329 BACKSIDED UCMEO 93001 10330 1630/ 10329 62024 80206 3582/ 203// 333// 41173 10329 61955 82105 ///// ///// 4112/ 99999 PLAIN SOHO/LASCO observed a Partial HALO CME on March 29, 2011. Event is first seen in C2 at 20:24 UT as a bright loop centered at PA 70 degrees followed by a deep cavity. The impulsive front expands with extensions PA 358-203 degrees for a total coverage of 205 degrees over the Eastern hemisphere. The event continues into the C3 field beginning 21:11 UT to 02:06 UT out to the edge of field, 30 Rsun. Time/height measurements were marked to 4 points in C2 with speeds of 1075.2 Km/sec at position angle 86 degrees. The event is marked to 9 points in C3 where it slightly accelerates. Speeds average through both fields to 1172.9.0 Km/sec at PA 83 degrees. STEREO EUVI 195 Behind shows an eruption of an AR in the NE beginning 19:55 - 21:05 UT with dimming and symmetric wave. STEREO COR2 B shows a partial halo over it's NE field beginning 20:54 UT. SDO/AIA 193 sees a cme from the AR over the NE limb beginning 19:59 UT. These events are most probably the cause of the HALO event seen in LASCO. 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/2011/110329/ Sam Freelands events page for this event is available with good information and found here: http://sdowww.lmsal.com/sdomedia/ssw/ssw_client/data/ssw_service_110329_221908_25547/www/ Best regards, Kevin Schenk Solar Heliospheric Observatory EIT and LASCO Operations NASA-Goddard Space Flight Center, USA BT