Date: Thu, 8 Apr 2004 14:56
From: Guillermo Stenborg
Subject: 'Full' Halo CME on 2004/04/08, frontsided
UCMEO 93001 40408 1900/
40408 61030 91642 0001/ 360// 123// 40915
40408 60953 81047 31115 10588 1122/
99999
PLAIN
BT
LASCO and EIT observed a full halo CME on 2004/04/08.
The event was first observed in C2 at 10:30 UT as a bright
loop front in the SSE; by 11:06 UT the front has developed
into a full halo CME, though much fainter in the northern
hemisphere. The front first appeared in C3 images at 10:42 UT,
though just slightly visible above the occultor. Full coverage
of the C3 occulting disk occurs by 12:18 UT. The mean plane-
of-sky speed for this event at PA 197 was 915 km/s (based only
in C3 data) showing a slight deceleration. For reference, the
mean plane-of-sky speed at different PA as obtained from C3
measurements is given below:
PA 020: 332 km/s
PA 117: 611 km/s
PA 265: 684 km/s
PA 300: 600 km/s
The CME was most probably associated with a C7.4 X-ray flare
that GOES records from AR 0588 (by the time at S15W11)
between 09:53 - 10:47 UT with peak emission at 10:19 UT.
EIT Fe XII running difference images show signatures of
the events between approximately 09:48 and 12:48 UT, the
flare peaking at 10:14 UT. A second intensity maximum can
be seen on the AR in the frame at 10:36 UT. Moreover, a large
disturbance traveling toward S (CME signature/wave?) can be
distinguished afterward. No dimming was observed in association
with the event. This event has therefore been determined
frontsided.
Please note that at 13:31 UT, at roughly the same PA where
our event first appeared in C2, another bright loop front starts
developing. This second event is likely related to a C1.3
X-ray flare registered by GOES, that occurred on the same AR
between 13:05 and 13:35 UT with peak emission at 13:20 UT. It
was also well imaged by EIT in Fe XII starting at around
13:13 UT.
Movies and images of the resulting complex event will shortly
be available at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20040408
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
++