Subject: SOHO/LASCO HALO CME 120304b

UCMEO 93001 20305 2030/
20304 61100 81542 0521/ 050// 333// 41362
20304 61100 81542 15716 11429 1112/
99999

PLAIN

SOHO/LASCO observed two (2) HALO CMEs on March 4, 2012.  The second event is 
first seen in C2 at 11:00 UT as a loop with cavity and core over the NE limb which 
expands with extensions to a full halo CME by 12:24 UT.
The event continues into the C3 field beginning 11:18 to 15:42 UT out to 30 Rsun
as it leaves the field of view in the NE.

Time/height measurements were marked to 4 points in C2 with speeds of 877.0 Km/sec
at position angle 54 degrees. The event is marked to 9 points in C3. Speeds average
through both fields to 1362.3 Km/sec at PA 53 degrees.  Acceleration 18.17 m/sec^s.


SDO/AIA 193 shows a flare of AR 11429 located at [N16,E57] beginning 10:30-12:00 UT. 
A dimming and a wave propagates in the east hemisphere followed by a  post loop
arcade.

STEREO: Beacon data
COR2 B, Beginning 11:25 UT, in progress, an asymmetric HALO CME over west.
Preliminary time/height measure gives 1300.5 km/sec velocity at LE. 
EUVI B, 10:36-11:46 UT flare and CME from AR 11429 near NW limb with wave over
the west hemisphere.
COR2 A, Beginning 22:24 UT, bright loop expanding over the east before data gap at
11:45 UT.
Preliminary time/height measure gives 978.9 km/sec velocity at LE. 
EUVI A, Loops seen rising over NE limb 10:25-10:45 UT.

NOAA reports a M2.0 Xray flare of AR 11492 10:29-12:16 UT.
   
The observation of this event is considered 'GOOD'. This CME is determined a FRONTSIDED 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/2012/120304b/

Best regards,

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

BT