Subject: SOHO/LASCO Partial HALO CME 110726 BACKSIDED

UCMEO 93001 10727 1630/
10726 61012 81906 2802/ 200// 113// 30967
///// ///// ///// ///// ///// /////
99999

PLAIN

SOHO/LASCO observed a Partial HALO CME on July 26, 2011.  Event is first seen in
C2 at 10:12 UT as a loop over the North pole region. The front expands quickly.
Material spans PA 280-200 degrees for a total coverage of 280 degrees. The event
continues into the C3 field beginning 10:42 UT to 19:06 UT out to 19.47 Rsun
where the event dissipates.

Time/height measurements were marked to 6 points in C2 with speeds of 1376 Km/sec
at position angle 16.5 degrees. The event is marked to 18 points in C3 where it
decelerates.  Speeds average through both fields to 967.6 Km/sec at PA 12.9 degrees.
Acceleration of -57.17 m/sec^

STEREO Becon data has data gaps:
COR2 B gap 07:55-12:40 UT.  Shows a CME in progress in the East field.
COR2 A gap 05:54-12:09 UT.  Shows a cme in progress in the West.
EUVI 195 B gap 07:56-12:26 UT.  No evidence.
EUVI 195 A gap 05:55-12:05 UT.  No evidence.
SDO/AIA does not show any evidence of the event on disk. 

These events are most probably the cause of the HALO event seen in LASCO.

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/2011/110726/


Best regards,

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

BT