Date: Tue, 11 Apr 2006 08:50
From: Guillermo Stenborg
Subject: Partial Halo Event on 2006/04/10, most probably backsided
Status: O
UCMEO 93001 60411 1250/
60410 60606 82342 1102/ 275// 113// 20200
60410 ///// ///// ///// ///// 5//2/
99999
PLAIN
BT
LASCO observed a very faint Partial Halo Event on 2006/04/10. It is
difficult to establish the time of first appearance due to its
faintness and the so diffuse aspect of the features involved.
Briefly, by around 06:06 UT a very diffuse and faint loop front
followed by a faint and expanding feature that extend later all above
the S Pole up to the W limb starts to be seen on SE. The expanding
feature is apparently first seen in C3 above the W Limb at ~ 11:18 UT.
It is difficult to track it accurately in C2 because it mixes up with
the trail of a previous limb event on W, already under development
(bright ragged front first seen in C2 on 04/09 at 22:30 UT -in C3 on
04/10 at 00:18 UT- on the W Limb, with diffuse extensions to N and S).
Note also that early on 04/10 the slow development of a system of faint
loops can be discerned in C2 on NW (first seen in C3 at 07:42 UT)
from which it is difficult to establish its association, if any,
to the bright loop front reported to start at 22:30 UT.
The mean plane-of-sky speed of the LE of our event at PA 151 was ~
200 km/sec (based on C3 data). The event apparently spans in the C3
FOV at 17:42 UT ~ 165 deg, from PA 110 - 275.
No frontsided signatures prior to the event on EIT 195 images, nor
X-ray events were reported by the time.
The event has therefore been determined as a faint Partial Halo Event
most likely backsided.
Movies and images of the event will shortly be made available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20060410
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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