Subject: SOHO/LASCO Partial HALO CME 120923 BACKSIDED

UCMEO 93001 20924 2030/
20923 61448 82118 2832/ 192// 333// 40956
20923 61316 81556 ///// ///// 2112/
99999

PLAIN

SOHO/LASCO observed a partial HALO CME on September 23, 2012.  Event is first seen
in C2 at 14:48 UT as a bright loop with cavity and core over the East limb.
The event expands with extensions PA 283 - 192 degrees for a total width of 269
degrees wide. The event continues into the C3 field beginning 15:42 to 21:18 UT
leaving the C3 field at 30 Rsun in the East.

Time/height measurements were marked to 5 points in C2 with speeds 
of 547.2 Km/sec at position angle 83 degrees. The event is marked to 13 points 
in C3. Speeds average through both fields to 956.2 Km/sec at PA 83 degrees.  
Acceleration 46.32 m/sec^2.

SDO/AIA 193 shows a multi-loop CME from behind limb beginning 14:15-15:36 UT on 
the equatorial East limb.
304 shows activated material over the East limb beginning at 13:21 UT.  An
eruptive prominence/filament is produced 14:18-15:42 UT resulting in CME.

STEREO: BEACON data
COR2 B, 15:25 UT a  symmetric halo with bright edge and cavity in the West.
Preliminary time/height measure gives 783.3 km/sec velocity at LE.
EUVI B, Activated loops west and adjacent to the AR located on disk at [S18, E111].
The filament erupts 13:16-15:56 UT producing a dimming and a small wave.
COR2 A, 15:24-15:54 UT in progress before going into a data gap beginning 15:54 UT.
EUVI A, no evidence. 

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/2012/120923/

Best regards,

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

BT