Date: Mon, 8 Nov 2004 17:11
From: Guillermo Stenborg
Subject: 'Full' Halo CME on 2004/11/08, frontsided
UCMEO 93001 41108 2210/
41108 60406 81418 0001/ 360// 123// 20520
41108 60212 80336 42008 10696 4122/
99999
PLAIN
BT
LASCO/EIT observed a 'full' halo event on 2004/11/08. Signatures likely
related to the event were first seen in the C2 FOV at 04:06 UT:
i) a faint and diffuse loop front above the S Pole, and ii) a
narrow and brighter ragged front developing toward NW preceded at
03:30 UT by ragged and not well defined narrow front. By 04:30 UT,
the C2 occultor is already completely covered by a rather symmetric
and diffuse halo. The signature marked as ii) is first seen in C3 at
04:18 UT surrounded by a diffuse front ahead of it. The 'halo' itself
covers the C3 occultor by 05:42 UT. For reference, the mean plane-of-
sky speed of the outermost front of the 'halo' at several PA is given
below:
PA 042: 443 km/sec
PA 214: 520 km/sec (taken for the UCMEO code)
PA 147: 430 km/sec
As for the elongated feature in NW, the mean plane-of-sky speed at
PA 318 was ~500 km/sec.
EIT 195 images show a brightening on NOAA AR 10696 starting
at ~02:12 UT, peaking at 02:24 UT, and followed by an intensity
disturbance (CME signature) developing apparently toward N, E, and S.
Another brightening can be distinguished at 03:36 UT, most likely
related to C7.9 X-ray flare (see below).
On the other hand, GOES recorded a C7.9 X-ray flare from NOAA AR
10696 (N08W20) between 03:25 - 03:36 UT with peak emission at 03:29 UT,
possibly associated to the event related to the features described
in ii). Please also note that the CME signature in EIT is before the
X-ray flare. Also several optical flares from nearby the AR were
reported, in particular at 02:24, 02:45, 03:00, and 03:30 UT (peak
emission).
In summary, the event as a whole has therefore been determined as a
'full' halo CME, frontsided. But again please keep in mind that in
fact a couple of events close in space and time occurred.
Movies and images of the complex event will shortly be made available
at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20041108
Best wishes,
Guillermo Stenborg
++
Dr. Guillermo A. Stenborg
SOHO-LASCO Operations Scientist,
CUA, MC 682.3, 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
++