SOHO/LASCO HALO CME 121123a

UCMEO 93001 21124 1750/
21123 61336 82230 1331/ 132// 323// 40570
21123 61127 81345 21637 ///// 2212/
99999

PLAIN

SOHO/LASCO observed two (2) HALO CMEs on November 23, 2012.  The first event (A)
is seen in C2 beginning 13:36 UT with a loop over the SE.  The event expands
with extensions to a total asymmetric halo by 15:36 UT.  The event continues into the
C3 field beginning 14:30-22:30 UT out to the edge of field at 30 Rsun in the South.

Time/height measurements were marked at 9 points in C2 with speeds of
427.5 Km/sec at pa 134 degrees. The event is marked to 10 points in C3.  
Speeds average through both fields to 570.3 Km/sec at PA 133 degrees.
Acceleration 24.82 m/sec^2. 

SDO AIA 193 and 304 shows an activated filament channel in the SW quadrant
located and centered at [S37, E16]. Filament erupted 11:27-13:45 UT producing  
a dimming and post loop arcade.

STEREO: BEACON data
COR2 A,  13:39 UT, expanding loops produce a partial Halo over the East.
Preliminary time/height measure gives 481.6 km/sec velocity, acceleration 13.60.
EUVI A 195, n/a
COR2 B, 13:40 UT, multiple events close in time produce a partial Halo in the West.
EUVI B 195,  n/a

The observation of this event is considered 'GOOD'. This CME is determined FRONTSIDED.

Images and movies and time/height information for this event is available on the web at:

http://umbra.nascom.nasa.gov/lasco/observations/halo/2012/121123a

Best regards,

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

BT