Subject: SOHO/LASCO HALO CME 100523

UCMEO 93001 00524 2100/
00523 61730 80142 3161/ 315// 113// 20223
00523 61624 82012 41217 ///// 2212/
99999

PLAIN

SOHO/LASCO observed a full HALO CME (type F) on May 23, 2010.  Event began in C2 at 17:30 UT
as an asymmetric elongated loop front centered over PA 316 degrees. The event slowly developed 
with the following of additional loops associated with the leading edge.  Material is seen at 
all positions for a total coverage of 360 degrees.  The event continues into the C3 field
beginning at 19:42 UT.   The CME tracked through the field and ends at approximately 01:42 UT 
to 12.2 Rsun.

Time/height measurements were marked to 18 points and calculated to velocities of this
event averaging 223. Km/sec at position angle 307 degrees.  

The event was first seen in EIT beginning at 16:24-20:12 UT with an impulsive filament eruption 
in the North West centered at [N17W12]. Event produced an elongated dimming north in the channel
and a long duration post arcading.

The eruption seen in EIT confirms a FRONTSIDED HALO event.

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

http://umbra.nascom.nasa.gov/lasco/observations/halo/2010/100523

Best regards,

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

BT