Subject: SOHO/LASCO Partial HALO CME 100117 -BACKSIDED

UCMEO 93001 00117 1750/
00117 60419 91415 3372/ 270// 232// 40603
00117 60413 80526 24390 ////// 5222/ 
99999

PLAIN

SOHO/LASCO C2 observed an asymmetric loop front at PA 115 degrees over the southeast quadrant
on January 17, 2010 04:19 UT.  By 05:28 UT a possible 2nd event starts northward of the
beginning position near PA 75 degrees.  This emission seems to cause a collision. The 
width of this event spans position angle range of 337 -270 degrees for a total 293 degrees.
The leading edge leaves the C2 field of view by 06:06 UT.  The event continues into the 
C3 field and measured in the last frame at the time of this writing of 14:15 UT.

Time/height measurements were marked and calculated to velocities of this event in the C2 
field of 602.9 Km/sec at position angle 95 degrees.  It slows into the C3 field and averages 
till 14:15 UT to 283.4 km/sec at the same position.

The event is seen in EIT as a BACKSIDED limb CME beginning at 04:13 UT at PA 127 degrees.  
Material is seen in range of PA 30-188 degrees.    At approximately 48 degrees a slower 
system over the limb is seen in difference images.  This may be an eruptive prominence 
but is activated in the same frame and are most likely related.

LASCO and EIT images, movies and time/height information for this event is available on the web at: 

http://umbra.nascom.nasa.gov/lasco/observations/halo/2010/100117/

Best regards,

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

BT