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Date: | Mon, 20 Sep 1999 10:02:19 -0500 |
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Sorry to take up so much bandwidth, but I thought would pass this on,
given the recent conversation-
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Sun-Earth Alert -------------------
On 16 September, a large (~ 50 degrees heliographic extent) and dark
solar filament (which is a prominence projected against the brighter
background of the Sun's disk) erupted and produced a large coronal
mass ejection. Later analysis revealed that although the majority of
mass ejected by this event was directed well northwest of the Earth
and out of the ecliptic plane, a small component appears to have been
directed Earthward. The velocity of this disturbance is fairly low and
will therefore require additional time to reach the Earth. But when it
does, there is a chance it could produce moderate enhancements in
auroral activity. The UTC day of 20 September looks to be the best
period of time for enhanced auroral activity. The disturbance is
projected to impact the Earth sometime late on 19 September or early
on 20 September.
This disturbance is not expected to be anything unusually spectacular,
but has a better than usual chance of producing periods of strong
auroral activity given the size and scale of the mass that was
involved with this solar coronal mass ejection. So although most of
the auroral activity is expected to remain confined to the higher
latitudes and not be particularly significant, there is a notably
slight chance activity could exceed expectations and become visible
over more widespread middle latitude areas.
The best times to observe activity will be near local midnight and
after
the moon sets in the early morning hours.
A full copy of the auroral activity watch has been included below for
completeness. For more information and near-realtime images and data
of auroral activity from the POLAR and TIROS satellites as well as
from ground-based observations from amateurs world-wide, visit the web
sites: http://solar.uleth.ca/www/aurora.html and
http://solar.uleth.ca/www/auroras.html.
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