Subject: SOHO/LASCO HALO CME 120307a

UCMEO 93001 20307 1630/
20307 60024 80318 0521/ 051// 333// 32405
20307 60006 80042 12117 11429 1112/
99999

PLAIN

SOHO/LASCO observed two (2) HALO CMEs on March 7, 2012.  The first event is seen in
C2 at 00:24 UT as a loop with cavity and core over the NE limb which expands to a full
halo CME by 00:48 UT. The event continues into the C3 field beginning 00:42 to 03:18 UT
out to 30 Rsun as it leaves the field of view in the East.

Time/height measurements were marked [20120307a] to 3 points in C2 with speeds of 2568.5 Km/sec
at position angle 54 degrees. The event is marked to 6 points in C3. Speeds average
through both fields to 2405.0 Km/sec at PA 52 degrees.  Acceleration 47.43 m/sec^2.
A second set of measurements were taken from the flank of the CME over the west.
[20120307b] marked to 4 points in C2 with speeds of 917.4 at pa 201 degrees.  Marked
to 7 points in C3.  Averaged speeds through both fields give 911.9 km/sec at pa 207
degrees with acceleration of 68.17 m/sec^2.

SDO/AIA 193 shows a flare of AR 11429 located at [N17,E21] beginning 00:06-00:42 UT.
A dimming is seen and a wave propagates across the east and north hemispheres.

STEREO: Beacon data
COR2 B, 3/6 21:25-01:25 UT data gap. Beginning 01:25 UT a full asymmetric halo
over the west field.  Leading edge is out of the field in first frame after gap.
EUVI B, 3/6 21:36-01:26 UT data gap. n/a
COR2 A, 3/6 22:39-05:24 UT data gap. n/a
EUVI A, 3/6 22:45-04:55 UT data gap. n/a

NOAA reports a X5.4 Xray flare of AR 11492 00:02-00:40 UT.
   
The observation of this event is considered 'FAIR'. 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/2012/120307ab/

Best regards,

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

BT