Date: Thu, 22 Jul 2004 14:42
From: Guillermo Stenborg
Subject: Frontsided events on 2004/07/22
UCMEO 93001 40722 1845/
40722 60731 81518 0001/ 360// 713// 20913
40722 60633 80810 11305 10652 1222/
99999
PLAIN
BT
LASCO/EIT observed a couple of significant events on 2004/07/22.
1) At 01:31 UT, an initially bright front is seen rising on the
S Pole in C2, with fainter loop-like extensions above the SW
Limb, and followed by much outflow on the S Limb. Later, by
05:30 UT, a ragged loop front can be discerned in the trailing
material. C3 shows the development of the event as, apparently,
two superposed ragged loop-like structures, one moving mainly
toward S and the other slightly toward NW. Globally, the event
spans in C3 ~ 100 deg at 07:42 UT, from PA ~ 140 - 240. The mean
plane-of-sky speed was around 500 km/sec, as measured at
PA ~ 180 and based on C3 data.
GOES recorded a M9.1 X-ray flare on NOAA AR 0652 (N03E13)
between 00:14 - 00:43 UT with peak emission at 00:32 UT. EIT
Fe XII running difference images record a strong brightening
on AR 0652 starting at 00:24 UT and peaking at 00:36 UT. Another
brightening occurs at 04:00 UT.
2) The second event, is more complex to describe due to the
occurrence of three C-class flares from the same AR between
06:33 - 08:10 UT. Basically, at 07:31 UT a bright narrow
feature appears above the S Pole in C2, preceding the
development of an asymmetric loop front at the S Pole with
faint loop-like extensions above the SW Limb. By that time,
an extremely faint and diffuse arcade-like front can be
discerned in C2 developing mainly toward NE, jointly with
another similar one toward NW. Their faintness makes it
difficult to establish the exact time of first appearance.
On the other hand, C3 shows, starting at 07:42 UT, the
development of a faint and diffuse wide loop front on NNE;
and starting at 08:42 UT a wide ragged loop front developing
on SSW. The former seems to surround later the occultor.
The mean plane-of-sky speed was around 913 km/sec, as measured
at PA ~ 210; and ~ 652 km/sec as measured at PA ~ 30 (based on
C3 data).
GOES recorded by the time several C-class X-ray flares on
NOAA AR 0652:
C1.7 (N05E13) between 06:33 - 06 43 UT; Peak at 06:38 UT
C2.1 (N04E12) between 06:54 - 07:07 UT; Peak at 07:00 UT
C5.5 (N03E08) between 07:41 - 08:10 UT; Peak at 07:59 UT
Fe XII running difference images show discernible brightenings
on AR 0652 at 06:36 UT and 07:48 UT (no images between 06:48 -
07:13 UT). No significant dimming or wave is observed in
association with the C-class events.
This second event has therefore been determined, from a global
point of view, as a faint '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/20040722
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
++