Subject: SOHO/LASCO HALO CME 110803a

UCMEO 93001 10803 1800/
10803 61348 91706 2131/ 212// 323// 41038
10803 61315 81421 42816 11261 1222/
99999

PLAIN

SOHO/LASCO observed a symmetric HALO CME on August 3, 2011.  Event is
first seen in C2 at 13:48 UT as material breaking over the occulter edge
on NW at 316 degrees. The second frame was a full halo CME with material
at all PAs. The event continues into the C3 field beginning 14:18 to 17:06 UT
at 16.5 Rsun, the last frame of event still in progress before a scheduled
DSN contact gap.

Time/height measurements were marked at 5 points in C2 with speeds of 882.0 Km/sec
at position angle 310 degrees. The event is marked to 10 points in C3 where it
accelerates.  Speeds average through both fields to 1037.8 Km/sec at PA 310 degrees.

SDO/AIA 193 shows a long duration flare of AR 11261 13:15-14:21 UT located 
at [N16 W28].  This event produced a AR dimming and a global wave.
STEREO:
COR2 A, 13:39 UT, a large burst with cavity and core over the East.
Preliminary height/time measure was taken on COR2 beacon data showing 1322.2 km/sec
COR2 B, 13:55 UT expanding burst in the west.  Measurements taken on beacon
data gave 1253.6 km/sec.
NOAA reports a M6.0 long duration xray flare of AR 11261 13:17-14:10 UT

This is most probably the cause of the FULL HALO event seen in LASCO.

   
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/2011/110803a/

Best regards,

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

BT