Date: Fri, 23 Jul 2004 17:53
From: Guillermo Stenborg
Subject: Frontsided Events on 2004/07/23
UCMEO 93001 40723 2200/
40723 61606 92118 0001/ 360// 517// 10990
40723 61603 81811 40405 10652 1222/
99999
PLAIN
BT
LASCO/EIT observed a couple of significant events on 2004/07/23,
one of them a 'full' Halo CME (#3).
1) At 23:54 UT (on 2004/07/22), a diffuse and not well defined
loop front is first seen above the SSW Limb. At 00:06 UT, a
bright narrow feature is discerned, superposed with the loop's
leg on the S Pole. Gusty outflow follows toward S. And later, at
01:54 and 02:30 UT, a couple of asymmetric loop fronts developing
toward SSW. C3 shows a very faint front developing mainly toward
SW, which is first seen at 00:42 UT. It fades rapidly. On the
other hand, Fe XII running difference images show discernible
brightenings on AR 0652 at 22:12 UT and 23:24 UT (no images
between 22:36 - 23:12 UT).
GOES recorded late on 2004/07/22 a couple of C- and one M-class
X-ray flares on NOAA AR 0652:
C4.1 (N03E04) between 22:01 - 22:18 UT; Peak at 22:12 UT
M1.6 (N04E03) between 22:40 - 23:07 UT; Peak at 22:58 UT
C1.3 (N03E02) between 23:09 - 23:45 UT; Peak at 23:21 UT
2) At around 07:31 UT another diffuse and not well defined loop
front is first seen above the SW Limb (difficult to give an exact
time of first appearance). A faint and diffuse loop-like front
follows, starting at ~08:30 UT above the W Limb. C3 shows a faint
front (though a little bit brighter than that of previous event)
developing mainly toward SW and spanning about 90 deg (first
seen in C3 FOV at 08:18 UT). Fe XII running difference images show
discernible brightenings on AR 0652 at 06:48 UT and 07:36 UT.
GOES recorded a couple of C-class X-ray flares by the time:
C2.3 (N03W04) between 06:41 - 07:02 UT; Peak at 06:48 UT
C4.3 (N03W04) between 07:17 - 07:36 UT; Peak at 07:26 UT
3) HALO CME:
The second event, is rather complex due to the occurrence of two
C- and one M-class flares from the same AR between 16:03 - 18:11 UT
(time of writing). Basically, at 16:06 UT a very faint and diffuse
loop-like front is first seen (just barely) above the W Limb in
C2, becoming rather bright and wide at 16:30 UT. Close inspection
of the development of the event in C2 show that several features
contribute to the evolution of the global pattern later observed,
i.e.:
i) a very wide and diffuse arcade-like front (most likely related
to [a] -see below-). It is first seen in C3, above the W Limb, at
16:42 UT. Mean plane-of-sky speed at PA ~ 270: 990 km/sec (though
very poor measurement due to the diffuseness of the leading edge,
based on C3 data).
ii) a ragged front that first appears at 17:54 UT above the WSW
Limb (most likely related to [b]). It is first seen in C3, above
the WSW Limb, at 18:18 UT. Mean plane-of-sky speed at PA ~ 245:
540 km/sec (based on C3 data, LE of brightest feature).
iii) another ragged front first seen above SW between 18:54 -
19:31 UT (most likely related to [c]). It is first seen in C3,
above the SW Limb, at 19:42 UT, though still almost hidden by
feature in ii). Mean plane-of-sky speed at PA ~ 204: 621 km/sec
(based on C3 data, LE of brightest feature, last point at ~ 11
solar radii).
GOES recorded by the time a couple of C- and one M-class X-ray
flares on NOAA AR 0652 (at the time of writing):
[a] C1.0 (N05W04) between 16:03 - 16:15 UT; Peak at 16:09 UT
[b] M2.3 (N03W10) between 17:08 - 17:37 UT; Peak at 17:28 UT
[c] C4.1 (N03W05) between 18:02 - 18:11 UT; Peak at 18:07 UT
Among significant features observed in Fe XII running difference
images it is worth to mention:
i) a kind of jet-like brightening at 16:12 UT on NOAA AR 0652
and developing toward SW [a], and
ii) a strong brightening [b] on the same AR at 17:24 UT with
associated ejecta of material toward SW (ejecta that seems to
disturb -push toward S- some loops on SW of the AR 0652); by
18:36 UT the loop system is no longer discernible).
This third event has therefore been determined, from a global
point of view, as a complex 'full' halo CME, frontsided (and
hence the one used for the UCMEO Code).
Images and movies of the whole set of events will shortly be
made available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20040723
Best wishes and a nice weekend,
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
++