Subject: SOHO/LASCO Partial HALO CME 120517b BACKSIDED

UCMEO 93001 20522 1330/
20517 61512 80006 3582/ 216// 123// 30401
20517 61335 81550 ///// 11471 2212/
99999

PLAIN

SOHO/LASCO observed a second partial HALO CME on May 17, 2012.  This Event
is first seen in C2 at 15:12 UT with a faint loop closely followed by a 
bright edge system.  Approximate width of the CME spans pa 358-216 degrees
totaling 218 degrees wide. The event continues into the C3 field beginning
16:06 to 00:06 UT where the CME dissipates at 21 Rsun in the East. A temporary
data gap is in the C3 data 18:06-21:44 UT.

Time/height measurements were marked to 9 points in C2 with speeds 
of 392.1 Km/sec at position angle 124 degrees. The event is marked to 10 points 
in C3. Speeds average through both fields to 400.7 Km/sec at PA 124 degrees.  
Acceleration -17.04 m/sec^2.

SDO/AIA, n/a

STEREO: HR data
COR2 B, multi-loop burst over the east beginning 14:54-18:54 UT,
Preliminary time/height measure gives 672.7 km/sec velocity at LE.
EUVI B, 195A 13:40 UT rising loops with eruption near SE limb.  Dimming with arcade.
EUVI B, 304A 13:65 UT, filament eruption along East edge and adjacent to AR 11471(?)
now on disk, close to the limb in the SE.
COR2 A, 14:39-17:54 UT Expanding loop over West hemisphere.
Preliminary time/height measure gives 666.4 km/sec velocity at LE.
EUVI A, 195A 13:45 UT CME with post arcade.
EUVI A, 304A FIlament material erupts from limb in SW beginning at 13:46 UT.

   
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/2012/120517b/

Best regards,

Kevin Schenk
Solar Heliospheric Observatory
EIT and LASCO Operations
NASA-Goddard Space Flight Center, USA

BT