Date: Mon, 28 Aug 2006 08:37
From: Guillermo Stenborg
Subject: Partial Halo Event on 2006/08/26, frontsided
Status: O
UCMEO 93001 60828 1245/
60826 62048 80542 0721/ 255// 123// 20730
60826 61952 82032 21011 10905 1//1/
99999
PLAIN
LASCO observed a Partial Halo Event on 2006/08/26-27. The event was first
seen in C2 on 08/26 at 20:48 UT just appearing above the occulting disk
on SSE. Two apparently different structures can be then distinguished
during its development: i) a very bright and expanding loop front developing
mainly toward SSE [Feature 1], and ii) a ragged and wider loop front
developing toward S, slightly behind [Feature 2]. The latter was first
clearly seen in C2 at 21:12 UT.
Feature 1 is first seen in C3 at 21:42 UT appearing on SSE, then
developing as a bright and ragged loop front, while Feature 2 shows up
above the S Pole by 22:18 UT. By 02:18 UT (on 08/27), the event considered
as a whole (and mainly due to Feature 2] spans ~ 183 deg (from about PA
072 - 255). The mean plane-of-sky speed of the outermost front of the event
(Feature 1] at PA 170 was ~ 730 km/sec (based on C3 data), showing
practically no acceleration. Note that the LE of Feature 1 becomes very
faint and diffuse by 00:42 UT (08/27). As for Feature 2, the mean-plane-of-
sky speed of its LE at PA 172 deg was ~ 585 km/sec.
GOES reported a C2.5 x-ray flare on NOAA AR 10905 (S11E10) between 19:52 -
20:32 UT with peak emission at 20:07 UT. EIT was in CCD Bakeout, therefore
no EIT images available.
In summary, the event has therefore been determined as a Partial Halo
Event, frontsided, associated with the C2.5 X-ray event on AR 10905.
LASCO/EIT movies and images of the event will shortly be made available
at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20060826
Best wishes,
Guillermo Stenborg
BT
++
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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