Halo CME Mail

Date: Tue, 9 Nov 2004 15:58

From: Guillermo Stenborg

Subject: Asymmetric 'full' halo CME on 2004/11/09, frontsided



UCMEO 93001 41109 2100/
41109 61726 92018 0001/ 360// 123// 21853
41109 61659 81732 45108 10696 1122/
99999
 
PLAIN
 
BT 


LASCO/EIT observed an asymmetric 'full' halo event on 2004/11/09. 
The event was first seen in C2 at 17:26 UT above the W and NW Limb 
as a very bright and wide loop front. By 17:50 UT, the LE already 
exited the C2 FOV (the event develops mainly toward NW). Faint 
extensions (shock?) up to NE. The C2 occultor is completely surrounded 
by the faint extensions by 18:26 UT, though on SE the excess intensity 
is just above the occulter. C3 images show the event starting at 
17:48 UT, on NW. By 18:18 UT, the C3 occultor is completely covered, 
the event having the appearance of a very asymmetric 'full' halo 
event. Please note that the 'bulk' of the mass, that is, the loop front
itself only spans from PA 215 - 360 (at 18:42 UT, measured in C3).
For reference, the mean plane-of-sky speed of the outermost layer of 
the 'halo' at several PA is given below:

PA 297: 1853 km/sec 
PA 004:  967 km/sec 
PA 224: 1236 km/sec
 
EIT 195 images show a strong brightening on NOAA AR 10696 starting 
at ~17:12 UT, and followed by an intensity disturbance developing 
across the Sun's surface with epicenter in the AR. On the other hand, 
GOES recorded a M8.9 X-ray flare from NOAA AR 10696 (N08W51) between 
16:59 - 17:32 UT with peak emission at 17:19 UT, most likely associated 
to the halo event. 

In summary, the event has therefore been determined as an asymmetric
'full' halo CME, frontsided. 

Movies and images of the event will shortly be made available at: 

ftp://ares.nrl.navy.mil/pub/lasco/halo/20041109

Please note that by 18:50 UT, C2 shows also a bright ragged loop front 
starting to  develop toward SE. That was just an event associated to 
activity on the SE Limb, as can be seen in the EIT images starting at 
17:36 UT.

Best wishes,
	Guillermo Stenborg

++
Dr. Guillermo A. Stenborg   
SOHO-LASCO Operations Scientist,                                           
CUA, MC 682.3, Bldg 26, Rm 001,   F: +1-301-286-0264         
NASA Goddard Space Flight Center,
Greenbelt, MD 20771.              P: +1-301-286-2941

e-mail: stenborg@kreutz.nascom.nasa.gov
++