Halo CME Mail

Date: Fri, 26 May 2006 11:13

From: Guillermo Stenborg

Subject: Faint Asymmetric Halo Event on 2006/05/26, frontsided


Status: O

UCMEO 93001 60526 1515/
60526 60006 80942 0001/ 360// 113// 20470
60525 62303 82343 32913 10884 1212/
99999
 
PLAIN


LASCO observed a faint asymmetric Halo Event on 2006/05/26. The event was
first seen in C2 at 00:06 UT, appearing above the WSW limb as an expanding 
and ragged loop front. The C2 occulting disk is apparently fully covered 
by 02:30 UT, the signal on E being just above the limb, while on W the LE
of the event is already past the C2 outer edge. The event is first seen in 
C3 at 00:42 UT, just appearing above the W Limb (barely visible on E, save
for the presence of an elongated loop front, whose association to the
main event is difficult to discern -if any-). The mean plane-of-sky speed
of the LE at PA 250 was ~ 470 km/sec showing a slight deceleration. 

GOES recorded a B5.4 X-ray flare on NOAA AR 10884 (S13W29) on 05/25
between 23:03 - 23:43 UT with peak emission at 23:28 UT. EIT 195 images
show a CME signature developing from AR 10884 toward SSW starting on 05/25 
at 23:12 UT. Also, formation of a dimming region to SSW of AR starting on
05/25 at 23:24 UT.

Note that prior to the C2 event, a faint and very diffuse loop-like front
is seen to appear in the C2 FOV at 19:31 UT on the W Limb, fading then close
to the inner edge of C3. A ragged loop front follows at 20:58 UT. Their 
development is much slower than previous reported event (therefore they
are quickly surpassed by the halo event). GOES recorded a couple of B-class
X-ray flares on NOAA AR 10885 (S12W21). They peaked at 18:30 UT (B1.3) and 
19:06 UT (B1.5). EIT 195 images show CME signatures between ~ 18:12 -
19:25 UT. Also, formation of a dimming region starting at ~ 18:36 UT
mainly to SE and S of AR 10885.


In summary, the LASCO event associated to the B5.4 X-ray event on AR 10884 
was catalogued as a very faint and asymmetric Halo Event, frontsided,  
preceded by a couple of frontsided events originated in a nearby AR
(10885).

LASCO movies and images of the whole chain of events will shortly be made 
available at:

ftp://ares.nrl.navy.mil/pub/lasco/halo/20060526


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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