Date: Thu, 4 May 2006 10:46
From: Guillermo Stenborg
Subject: Partial Halo Event on 2006/05/04, frontsided
Status: O
UCMEO 93001 60504 1445/
60504 60131 91218 1101/ 255// 213// 20520
60504 60024 80136 32517 ///// 2212/
99999
PLAIN
LASCO/EIT observed a Partial Halo Event on 2006/05/04. The chain of events
started late on 05/03 when a narrow, elongated, and apparently twisted
feature starts to develop above the SW limb of C2 (first clearly seen
at 23:30 UT, however some brightenings could be seen since a little bit
earlier). Associated to this apparently unconspicuous event, EIT 195
images showed a prominence eruption to S of NOAA AR 10875 between around
23:12 - 23:48 UT.
Afterward, a small brightening just appearing to S of previous event
starts to be seen in C2 on 05/04 at 01:31 UT. It develops as a ragged and
expanding loop front [1], and is then followed by a structured core (its
inner front first seen in C2 at 02:54 UT) [2]. By 03:30 UT, a system of
faint and expanding loop fronts start to be visible above the S Pole [3].
By 06:54 UT, this system of loops spans ~ 145 deg (from PA 110 - 255 in
the C2 FOV). Feature [1] is first seen in C3 appearing above the SW Limb
at 03:18 UT. Feature [2] follows behind at 04:42 UT. Finally, Feature [3]
shows up above the S Pole at 05:42 UT, partly superposed in the LOS with
[2]. The mean plane-of-sky speed of the different features involved is
as follows (based on C3 data):
Feature [1] at PA 226: 520 km/sec (showing practically no acceleration)
Feature [2] at PA 225: 400 km/sec (showing practically no acceleration)
Feature [3] at PA 187: 300 km/sec (showing practically no acceleration).
The measurements corresponding to Feature [3] is not that reliable due to
the faintness of its LE (and superposition with Feature [2]).
GOES reported no significant X-ray activity by the time prior to the
LASCO C2 event, though it recorded a B3.7 X-ray flare on NOAA AR 10876
(S17W41) between 03:28 - 05:00 UT with peak emission at 04:35 UT. EIT 195
images show between ~ 00:24 - 01:36 UT the eruption of the rest of the
filament (see first paragraph in this report) between AR 10876 and E05.
It is visible at least as far as the skirt of the South Polar Coronal Hole
at ~ S60. EIT shows then, between ~ 01:13 - 06:48 UT, the slow evolution
of post-CME loops to SE of AR 10876.
In summary, the event has therefore been catalogued as a Partial Halo
Event, frontsided, associated to a filament eruption.
LASCO movies and images of the event will shortly be made available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20060504
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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