Subject: SOHO/LASCO HALO CME 120929 BACKSIDED

UCMEO 93001 21001 2230/
20929 60012 80718 0802/ 079// 313// 30611
20928 62256 80026 ///// ///// 1112/
99999

PLAIN

SOHO/LASCO observed a HALO CME on September 29, 2012.  Event is first
seen in C2 at 00:12 UT as a faint loop surfacing in the Southwest which
produced a symmetric halo at 00:36 UT.  The event continues into
the C3 field beginning 00:42 to 07:18 UT where the event dissipates at 19.5 Rsun.

Time/height measurements were marked to 3 points in C2 with speeds 
of 727.8 Km/sec at position angle 84 degrees. The event is marked to 6 points 
in C3. Speeds average through both fields to 610.8 Km/sec at PA 80 degrees.  
Acceleration 42.73 m/sec^2.

SDO/AIA : n/a

STEREO: BEACON  Data
COR2 B, 23:55-00:25 UT data gap. In progress, loop expanding over SE.
Preliminary time/height measure gives 945.3 km/sec velocity at LE.
EUVI B, 17:16-22:26 UT data gap. At 22:56 and 23:06 UT, 2 flares from different regions
in close proximity on the limb in East.  Both appear to be associated with the halo.
COR2 A, 16:54-02:54 UT data gap.  n/a
EUVI A, 17:15-03:05 UT data gap. n/a

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/2012/120929/

Best regards,

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

BT