Date: Fri, 13 Jan 2006 12:19
From: Guillermo Stenborg
Subject: At least Partial Halo Event on 2006/01/12, most likely backsided
Status: O
UCMEO 93001 60113 1720/
60112 61530 80342 0652/ 280// 123// 30475
60112 ///// ///// ///// ///// 5//2/
99999
PLAIN
BT
LASCO observed an (at least) Partial Halo Event on 2006/01/12.
Signatures of the event (a diffuse brightening) started to be seen
in C2 at 15:30 UT barely above the SSE limb. A bright and expanding
loop front follows at 15:54 UT on the S Pole. Some trailing material,
in particular some relatively narrow loop fronts on SSW starting at
around 17:54 UT. By the end of the day, the event seems to cover
completely the C2 occulting disk (the LE on S well past the outer
edge of the C2 FOV, while very weak signal barely above the occulting
disk on N).
The event is first seen in C3 at 16:42 UT just appearing above the
SSE. The bright loop front is well seen on the S by 17:18 UT. By
23:18 UT the event spans in the C3 FOV about 215 deg (from PA ~
065 - 280). Afterward, the legs become too faint to determine whether
the C3 occulting disk gets completely covered. The mean plane-of-sky
speed of the LE of the event at PA 170 was ~ 475 km/sec, showing
an slight acceleration.
GOES recorded no significant X-ray activity during the day (below
the A level). Likewise, EIT 195 images do not show any significant
event the disk by the time prior to the LASCO C2 event. Therefore,
the event has been determined as at least a Partial Halo Event, most
likely backsided, based on the lack of X-ray (GOES) and EUV (EIT 195)
activity.
NOTE:
However, EIT shows much later the lift-off of a filament located at
around S03W16 (at 23:50 UT). C2 shows the development of a bright loop
front on W starting at 00:54 UT on 01/13 with some very faint and
diffuse extensions to N, and a twisted --like circularly structured--
interior. This event becomes visible in C3 at 02:42 UT, appearing above
the W Limb. Its angular extent at ~ 07:42 UT is about 70 deg (from PA ~
240 - 310).
Movies and images of the Partial Halo event (including also the filament
eruption) will shortly be made available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20060112
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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