Subject: SOHO/LASCO HALO CME 110201 BACKSIDED

UCMEO 93001 10201 2015/
10201 62336 80454 0292/ 028// 113// 30373
10201 62236 82306 ///// 11149 4222/
99999

PLAIN

SOHO/LASCO observed an asymmetric HALO CME on February 1, 2011.  Event is first seen in 
C2 at 22:36 UT as a faint elongated loop over the north pole and northeast quadrant.  
The loop expands and develops to FULL HALO CME by 00:36 UT with associated material at all
positions. The event is seen in first frame of C3 at 00:42 UT, expanding over the north 
and tracked out to 04:54 UT at 11.5 Rsun where the event dissipates.
 
Time/height measurements were marked to 8 points from 2.5 - 6.4 Rsun in C2 with speeds 
of 419 km/sec, the event decelerates in C3, marked at 12 points and calculated to
velocities averaging thru both fields to 373.0 Km/sec at position angle 29 degrees.    

STEREO EUVI 195A Behind beacon data shows a cme from AR 11149/11147 grouping in it's 
northeast quadrant at the limb beginning 22:36 - 23:06 UT. EUVI 195A Ahead also saw
the CME from the same region on it's northwest quadrant. 
SDO AIA sees a backsided CME in the northeast beginning 2/1 22:49 UT.
There were no Earthward facing events or activity.
   
The observation of this event in LASCO is considered 'fair'. This CME is determined a BACKSIDE 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/2011/110201/

Best regards,

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

BT