Date: Mon, 6 Nov 2006 12:50
From: Guillermo Stenborg
Subject: Backsided event on 2006/11/05, with some signatures extending to the , front side
Status: O
UCMEO 93001 61106 1650/
61105 61730 80032 0002/ 360// 13// 31520
61031 ///// ///// ///// ///// 51/2/
99999
PLAIN
LASCO observed an at least Partial Halo Event on 2006/11/05. The
event was first seen in the LASCO C2 FOV as a bright narrow front
above the E Limb at 17:30 UT, which by 17:54 UT developed as a big
and very bright loop front. At this time the LE on E is already
past the outer edge of the C2 FOV. Faint and diffuse extensions
develop up to past the N Pole. By 18:54 UT the diffuse extensions
seem to cover the C2 occulting disk (signal much fainter above the
S Pole). The event was first seen in C3 at 17:42 UT as a narrow
front just showing up above the E Limb. By 18:18 UT, a wide and
bright loop front spans all above the NE limb, with faint extensions
up to past the N Pole. The signal is too faint to be discernible
above the S Pole. The mean plane-of-sky speed of the LE at PA ~ 70 deg
was ~ 1520 km/sec. No significant X-ray activity was detected by
GOES related to this event (either in time or space). Just for
completeness, note that there was a C3.7 X-ray flare on NOAA AR
10921 (S06W13) between 12:16 - 12:340 UT with peak emission at
12:40 UT. Likewise, EIT 195 images do not show significant frontsided
activity related to the event, although they do show a rather
important backsided (apparently close to the limb) CME event all
above the NE Limb starting at around 17:24-17:36 UT (EIT counterpart of
the LASCO event). A wave can be seen developing on the eastern side of
the solar disk coming from behind the E limb starting at 18:42 UT.
Note that there are no LASCO images between 20:21 - 24:00 UT (C2 time)
due to a special observation program for Mars Express and Venus
Express Campaign.
In summary, the event has therefore been determined as an at least partial
halo event, backsided, based on the signatures observed in EIT 195 images.
Please be aware that some signatures of the event (an EIT wave) extended
to the front side.
Movies and images of the event will shortly be made available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20061105
NOTE:
Please note that there was a similar backsided event on 2006/11/03
(an at least Partial Halo Event backsided). A short description
follows: At 19:31 UT a very bright and big loop front appears in the C2
FOV on NE with diffuse extensions that span up to past the N Pole. The
LE already midway to the end of the C2 FOV. Only one C3 frame captured
the event (19:42 UT) due to the fact there was no LASCO CME watch
between 20:21 - 24:00 UT due to a special observation program for
Mars Express and Venus Express Campaign. No significant X-ray activity
was recorded by GOES by the time (B-class). EIT 195 running difference
images do show signatures of a rather important backsided event all
above the NE limb starting at 19:13 UT. The development was missed in
the data gap mentioned above.
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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