Halo CME Mail

Date: Tue, 8 Aug 2006 11:02

From: Guillermo Stenborg

Subject: Very faint Halo Event on 2006/08/07, most probably backsided


Status: O

UCMEO 93001 60808 1505/
60807 60131 82042 0002/ 360// 113// 10170
60807 ///// ///// ///// ///// 5//2/
99999
 
PLAIN


LASCO observed a faint Halo Event on 2006/08/07. The event was first seen 
in C2 at around 01:31 UT, appearing above the NW limb: a faint expanding 
loop front apparently preceded by a fainter and expanding front. The 
latter fully surrounds the C2 occulting disk by around 07:37 UT. The halo 
signature has elliptical shape (by that time the LE on NW is close to the
end of the C2 FOV, and barely above the limb on SE). Note that gusty
outflow (and some ragged fronts) can be seen along the day on SW. The halo 
event is first seen in C3 at ~ 08:20 UT on NW, just behind the pylon. The 
event is no longer discernible in C3 by 20:42 UT. It didn't reach the end 
of the FOV by that time (outermost part at ~ 17 solar radii -on NW-). The 
mean plane-of sky speed of the LE at PA 162 was ~ 170 km/sec. The accuracy 
of the measurements is poor due to the faintness and diffuseness of the
LE.

GOES recorded no significant X-ray activity during the day (A-level).
Likewise, EIT 195 images do not show significant frontsided activity save 
some faint brightenings and apparent outflow to NW of a bright region on
the SW quadrant (signature compatible with the C2 gusty outflow mentioned
in first paragraph). 

In summary, the event was catalogued as a very faint and slow Halo Event,
most probably backsided based on the lack of activity at the appropriate 
location to be considered frontsided.
 
LASCO movies and images of the event will shortly be made available at:

ftp://ares.nrl.navy.mil/pub/lasco/halo/20060807


Best wishes,
	Guillermo Stenborg
	

++
Dr. Guillermo A. Stenborg   
SOHO-LASCO Operations Scientist,                                           
CUA, MC 612.5, 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
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