Subject: SOHO/LASCO HALO CME 100801

UCMEO 93001 00801 1845/
00801 71418 91718 0091/ 008// 113// 10425
00801 60725 81005 13520 11092 1222/
99999

PLAIN

SOHO/LASCO observed a full asymmetric HALO CME (type A) on August 1, 2010.  Event is first seen in 
C3 at 14:18 UT already in progress.  The closest point at 9.02 Rs at PA 11 degrees, farthest
point 14.53 Rs at PA 130 degrees.  At this time SOHO is in the quarterly telemetry 'Keyhole' period. 
(http://soho.nascom.nasa.gov/hotshots/2004_01_04/)
SOHO was out of real-time contact and data not recorded 01:45 - 13:40 UT.  When we came into contact
the event had already passed through the C2 field of view.

Time/height measurements were marked to 6 points in C3 and calculated to velocities of this
event averaging 424.9 Km/sec at position angle 9 degrees.    

EIT did not see the event start. EITs first frame was 13:48 UT showing a bright post loop arcade of
AR 11092.  STEREO Ahead EUVI 195A beacon data shows AR 11092 over the East limb with a large CME
beginning at 07:25 UT. By 10:35 UT a bright long duration loop arcade develops and rises over limb.
NOAA reports a C3.2 Xray flare of AR 11092 beginning at 07:55 UT, located at [N20, E35]. This is
most probably the cause of the event seen in LASCO.
   
The observation of this event is considered 'poor'. The gathered information is enough to warrant 
this CME as 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/2010/100801/

Best regards,

Kevin Schenk
SOHO Mission
EIT and LASCO Operations
NASA-Goddard Space Flight Center, USA

BT