SOHO/LASCO HALO CME 111120 BACKSIDED

UCMEO 93001 11121 1900/
11120 62312 80530 0282/ 027// 223// 30791
11120 62126 80005 ///// /////
99999

PLAIN

SOHO/LASCO observed a HALO CME on November 20, 2011.  Event is
first seen in C2 at 23:12 UT as a loop front over the north which
propagates to a full HALO CME by 00:12 UT.  This event appears to
be 2 systems with slight speed difference in lower flanks.  It
continues into the C3 field beginning 23:18 to 05:30 UT where it
dissipates at 20 Rsun.

Time/height measurements were marked at 5 points in C2 with speeds of 795.0 Km/sec
at position angle 28 degrees. The event is marked to 6 points in C3 where it
slows.  Speeds average through both fields to 791.0.1 Km/sec at PA 28 degrees. 

SDO/AIA 193 shows LE emission over the NW limb at 21:15 UT and a second set at
22:09 UT in difference movie.
STEREO: Beacon data
COR2 B, 22:40 UT in NE, partial halo over east hemisphere.
Preliminary time/height measure gives 743.2 km/sec velocity at LE.
EUVI B 195, CME behind NE limb above equator at 21:26 UT and a CME
at 22:56 UT from an AR on limb in SE just below equator. 
COR2 A, 22:39 UT over NW.  Full halo by 23:54 UT. 
Preliminary time/height measure gives 771.0 km/sec velocity at LE.
EUVI A 195, a CME 21:55 UT from AR in NW at 22:55 a CME from AR on limb in SW.
COR2 A and EUVI A data gap 00:54-03:39 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/2011/111120/

Best regards,

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

BT