Subject: SOHO/LASCO Partial HALO CME 100228 - Backsided

UCMEO 93001 00229 2220/
00228 61254 80042 2612/ 073// 123// 40415
00228 61236 82224 1//// ///// 3222/ 
99999

PLAIN

SOHO/LASCO observed a partial HALO CME (type P) on February 28, 2010.  Event began in C2 at 12:54 UT 
as a wide symmetric slow loop front over the North Pole, centered approximately at PA 350 degrees.
This CME progressed to an active multi-loop with core and scattered bulk materials as it expands
with material eventually seen from PA 261 - 73 for a total coverage of 172 degrees. By 18:54 UT
a burst comes over the NE at PA 70 degrees followed by an asymmetric loop with core(s). This could
possibly be a shock event disturbed by the 12:54 UT halo.
The event continues into the C3 field beginning at 16:18 UT over the North Pole and measured through 
the field as the event ends at approximately 3/1 00:42 UT to 27 Rsun.

Time/height measurements were marked to 30 points and calculated to velocities of this
event averaging 415.6 Km/sec at position angle 340 degrees through C2 and C3. 

EIT sees a slow far-side CME beginning at 12:36 - 22:24 UT in the NE centered at PA 30 degrees.  This
most possibly pertains to the event seen in LASCO.  This event is determined a BACKSIDED HALO event.

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

http://umbra.nascom.nasa.gov/lasco/observations/halo/100228

Best regards,

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

BT