Date: Mon, 24 May 2004 11:04
From: Guillermo Stenborg
Subject: 'Full' Halo CME on 2004/05/23, backsided
UCMEO 93001 40524 1505/
40523 61106 82042 0002/ 360// 123// 30693
///// ///// ///// ///// ///// /////
99999
PLAIN
BT
LASCO observed a full halo CME on 2004/05/23. The event was
first observed in C2 at 11:06 UT developing as a very bright
ragged loop front above the W limb. Very faint extensions
are first seen to N at 11:50 UT. By 12:50 UT the C2 occultor
is completely covered. The front first appeared in C3 images
at 11:42 UT as a thick and bright ragged loop front above the
W Limb, the bulk of the ejecta developing toward W. By 15:18 UT
the C3 occultor is completely covered. By that time, the LE of
the front on W Limb is already at about 18.5 solar radii. The
mean plane-of-sky speed for this event at PA 267 was 693 km/s
(based only in C3 data). For reference, the mean plane-of-sky
speed at different PA as obtained from C3 measurements is given
below:
PA 006: 281 km/s
PA 045: 240 km/s
PA 326: 366 km/s
EIT Fe XII running difference images show signatures of a big
CME coming out from behind the disk, all above the West limb,
since 11:00 UT. An intensity disturbance is seen to travel
toward N and S (always above the limb) as the event develops.
GOES recorded a B4.3 X-ray flare between 11:30 and 11:43 on
NOAA AR 10618, by the time at S12E32, which most likely has no
association with the halo event. This event has therefore been
determined as a 'full' (asymmetric) halo CME, backsided.
Movies and images of the event will shortly be available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20040523
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
++