Subject: SOHO/LASCO Partial HALO CME 120517a UCMEO 93001 20517 1800/ 20517 60148 80530 1701/ 011// 333// 31618 20517 60127 80239 47611 11476 1112/ 99999 PLAIN SOHO/LASCO observed partial HALO CME on May 17, 2012. Event is first seen in C2 at 01:48 UT as a bright loop with cavity and core in the West. The approximate width of the CME spans pa 170-11 degrees totaling 201 degrees wide. The event continues into the C3 field beginning 01:54 to 05:30 UT where it leaves the field at 30 Rsun. Increased proton emission is seen in the lasco white light images. Time/height measurements were marked to 2 points in C2. The event is marked to 9 points in C3. Speeds average through both fields to 1617.9 Km/sec at PA 270 degrees. Acceleration -46.98 m/sec^2. SDO/AIA 193 shows a long duration flare of AR 11476 located at [N11,W76] beginning 01:27-02:39 UT. The event produces a wave across the west hemisphere and dimming southward. AIA 304 shows an eruptive filament beginning after the flare 02:36-03:12 UT coming near AR from behind limb. STEREO: Beacon data COR2 A, 20:54-02:24 UT data gap. 02:24 UT first frame partial halo east,LE at 6 Rsun. Preliminary time/height measure gives 1047.5 km/sec velocity at LE. EUVI A, 20:45-02:25 UT data gap. 02:25 UT in progress, dimming south and westward from AR 11476 on disk in NE. Filament at disk center on east edge of large coronal hole erupts 02:25-03:25 UT with post ribbon. COR2 B, 20:54-05:24 UT data gap. n/a EUVI B, 21:05-05:25 UT data gap. n/a NOAA reports a M5.1 Xray flare of AR 11476 01:25-02:14 UT. An instant increase in proton flux is shown, particles at >100 MeV peaked above storm level conditions. The observation of this event is considered 'FAIR'. 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/2012/120517a/ Best regards, Kevin Schenk Solar Heliospheric Observatory EIT and LASCO Operations NASA-Goddard Space Flight Center, USA BT