Date: Mon, 26 Jul 2004 12:13
From: Guillermo Stenborg
Subject: 'Full' Halo CME on 2004/07/25, frontsided
UCMEO 93001 40726 1615/
40725 61430 82318 0001/ 360// 233// 31228
40725 61318 81643 43004 10652 1222/
99999
PLAIN
BT
LASCO/EIT observed a 'full' Halo CME on 2004/07/25. The event
was first seen in C2 at 14:30 UT developing as an extremely
bright loop front, preceded at 13:31 UT by a faint kind-of
asymmetric loop front (quickly surpassed by the loop front). By
15:30 UT, faint extensions in the western hemisphere, and even
fainter ones on the N Pole surround the C2 occultor. A fainter
second front is seen to appear later above the SW Limb in C2,
at 15:54 UT. Gusty outflow follows at PA around 225. The event
is first seen in C3 at 15:18 UT above the SW Limb. By 15:52 UT,
faint extensions already surround the C3 occultor. For reference,
the mean plane-of-sky speeds at several PA is given below (based
only on C3 data):
PA 005: 814 km/s
PA 145: 1228 km/s
PA 224: 1081 km/s
PA 262: 1167 km/s
GOES recorded by the time a couple of M- and one C-class X-ray
flares on NOAA AR 0652:
C2.1 (N04W29) between 13:18 - 13:32 UT; Peak at 13:25 UT
M2.2 (N04W30) between 13:37 - 13:55 UT; Peak at 13:49 UT
M1.1 (N08W33) between 14:19 - 16:43 UT; Peak at 15:14 UT
Among significant features observed in Fe XII running difference
images it is worth to mention: i) a moderate brightening at 13:26 UT
on NOAA AR 0652, signature of the C2.1 X-ray flare; ii) a strong
brightening on the same AR at 13:48 UT (signature of the M2.2 X-ray
flare) with associated ejecta of material toward SW (ejecta that
seems to disturb -push toward S- some loops on SW of the AR 0652);
and iii) another couple of brightenings in the same AR peaking by
15:00 UT and 16:00 UT (most likely signatures of the relatively
long duration M1.1 X-ray event). Please also note that at 14:48 UT,
an expanding system of loops develops on the WSW Limb, apparently
with its source just behind the limb (by 16:00 UT post-flare loops
can be discerned raising from behind the limb).
The event has therefore been determined as a complex 'full' halo
CME, frontsided.
Images and movies of the whole set of events will shortly be made
available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20040725
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
++