Halo CME Mail

Date: Mon, 31 Dec 2001 13:41

From: Gareth Lawrence

Subject: Full Halo CME on 2001/12/30, most probably backsided

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LASCO observed a full halo CME on 2001/12/30. A bright loop front was
first seen at 23:30 UT in the SW, filling most of that quadrant, and
this had developed to a full halo CME by 00:30 UT. The front first
appeared in C3 at 00:18 UT and was a full halo CME by 00:42 UT,
although emission in the N and NE is faint in C3.

The EIT data show no obvious candidate for a frontsided event within
a realistic timeframe. An eruptive prominence can be seen between
22:00 - 23:12 UT in the SW, but this event can be seen in LASCO
data between 22:30 - 23:06 UT, just before the leading edge of the
halo first appears. The earlier event can also be seen in C3 data
between 23:18 - 23:42 UT, again before the leading edge of the halo
CME first appears. The prominence lifted off from a region centered
around S30W54 and there is no evidence that it disrupted the on-disk
region to the N or E of it. Also, the halo first appears centered
about PA 200, some 35 degrees away in projection.

Thus, whilst it is possible that the erupting prominence seen by EIT
and LASCO is in some way associated with the halo CME, we feel it
seems most probable that the halo CME was backsided, at very least
for the greater part.

Best wishes,
        Gareth Lawrence

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| Gareth Lawrence,                   E-mail:grl@kreutz.nascom.nasa.gov |
| SOHO-LASCO Operations Scientist,                                     |
| CUA, Mail Code 682.3,                                                |
| NASA Goddard Space Flight Center,      Phone:  +1-301-286-2941       |
| Building 26, Room G-1,                         +1-301-286-3447       |
| Greenbelt, MD 20771.                   Fax:    +1-301-286-0264       |
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