Date: Mon, 8 Nov 2004 14:28
From: Guillermo Stenborg
Subject: 'Full' Halo CME on 2004/11/07, frontsided
UCMEO 93001 41108 1930/
41107 61718 80342 0001/ 360// 123// 31770
41107 61542 81615 41709 10696 1122/
99999
PLAIN
BT
LASCO/EIT observed a 'full' halo event on 2004/11/07. Several events
related to high activity on AR 10696 are first seen in C2 before the
'big' event. In particular it is worth to mention the appearance of
a brigh loop front above the NW Limb, developing superposed in the
LOS with the slow evolution of a system of loops along the streamer.
By 17:06 UT, the event is completely surpassed by a bright and very
wide loop front, developing mainly toward NW, with faint extensions
on S that give to the event the appearance of a full halo CME from
its very beginning. The halo event is first seen in C3 at 17:18 UT.
Please note that the previous front first appeared in C3 at 16:18 UT,
being completely surpassed by the halo event at 17:18 UT. During the
evolution of the halo event in the C3 FOV, a proton storm develops,
becoming stronger by 21:30 UT (C2 time).
The mean plane-of-sky speed of the LE of the outermost front at PA 2
was ~ 1770 km/sec (based on C3 data) showing practically no
acceleration. If taken into account the LE as the outermost part of
the brightest feature (not the outermost one), the mean speed was
1460 km/sec at PA 356. And just for reference, the mean plane-of-sky
speed of the outermost front at:
PA 052: 1180 km/sec
PA 229: 1100 km/sec
GOES recorded high X-ray activity with several B- and C-class X-ray flares
all along the day from NOAA AR 10696. In particular, note the X2.0 X-ray
flare from that AR (N09W17) between 15:42 - 16:15 UT with peak emission
at 16:06 UT, most likely associated to the Halo event. It is also worth to
mention the C7.0 X-ray flare (N08W14) between 13:58 - 14:20 UT with
peak emission at 14:07 UT, most likely related to the 'first' event,
reported to be seen on NW.
On the other hand, EIT 195 images show a brightening on the aforementioned
AR starting at ~14:00 UT, followed at 15:12 UT by the apparent ejection
of material toward NW. By 16:00 UT, a very strong brightening is seen
to occur above the aforementioned AR (signature of the X2.0 X-ray flare)
followed by a strong intensity disturbance travelling acroos the disk with
epicenter in that AR (the disturbance is stronger toward N).
For completeness, please note that the C3 images show, starting at about
21:18 UT, signatures of what it could be considered as an apparent much
fainter and ragged halo in the aftermath of the previous big halo event.
In summary, the event as a whole has therefore been determined as a 'full'
halo CME, frontsided. But please keep in mind that 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/20041107
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Erratum:
Please note that in previous Alert (Event on 2004/11/06) where it says:
"GOES recorded three X-ray flares almost one after another form NOAA
AR 10696, by the time at N08E18:"
it should say:
"GOES recorded three X-ray flares almost one after another from NOAA
AR 10696, by the time at N10E08:"
Sorry for the typo.
--------
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
++