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dsktc
09-14-2004, 12:20 AM
For anyone who wants to try the
nearly impossible task of photographing
a train and the Aurora Borealis:

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This Is SKY & TELESCOPE's AstroAlert for Sun-Earth Interactions
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A s t r o A l e r t
Sun-Earth Alert

Solar Terrestrial Dispatch
http://www.spacew.com

13 September 2004


AURORA WATCH IS ACTIVE EFFECTIVE IMMEDIATLEY - 13 Sept

The coronal mass ejection mentioned in the last AstroAlert was
associated with a much higher velocity than solar radio observations
suggested. The disturbance crossed the distance from the Sun to the
Earth much faster than anticipated and impacted the Earth near 20:02
UTC on 13 September. The disturbance has the potential to produce
periods of visible auroral activity across fairly wide-spread middle
latitude regions during the next 12 to 24 hours.

The middle latitude auroral activity watch has been engaged and
is presently active. It will remain active through 18:00 UTC on 16
September, although the bulk of the strongest activity will occur
within the next 12 to 18 hours. Interested observers should watch the
night sky TONIGHT for signs of activity.

A copy of the revised auroral activity watch for the middle
latitudes is included below.


MIDDLE LATITUDE AURORAL ACTIVITY WATCH
Issued: 20:25 UTC, 13 September 2004
Solar Terrestrial Dispatch
www.spacew.com


VALID BEGINNING AT: EFFECTIVE IMMEDIATELY
VALID UNTIL: 18:00 UTC (7 pm EDT) ON 16 SEPTEMBER

PREDICTED IMPACT TIME OF DISTURBANCE: IN-PROGRESS !

HIGH RISK PERIOD: 14-15 SEPTEMBER
MODERATE RISK PERIOD: 14 - 16 SEPTEMBER

PREDICTED ACTIVITY INDICES: 35, 17, 15, 15 (13 - 16 SEPTEMBER)

POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE

POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 12 TO 18 HOURS
MINOR BELT = 18 TO 24 HOURS

ESTIMATED OPTIMUM OBSERVING CONDITIONS: NEAR LOCAL MIDNIGHT

EXPECTED LUNAR INTERFERENCE: NONE

OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR TO
GOOD

AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE
FROM...

NORTHERN OREGON TO SOUTHERN IDAHO TO WYOMING TO SOUTH DAKOTA TO
ILLINOIS TO OHIO TO NORTHERN VIRGINIA TO MARYLAND.

ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...

ENGLAND TO NORTHERN BELGIUM TO NORTHERN GERMANY TO NORTHERN
POLAND TO NORTHERN BELARUS TO NORTH-CENTRAL RUSSIA.

ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY SOUTH OF A LINE FROM...

NEW ZEALAND TO EXTREME SOUTHERN AUSTRALIA.


SYNOPSIS...

The aforementioned coronal mass ejection has arrived much
earlier than predictions suggested. This is due to an unexpectedly
high transit velocity.
The velocity of the disturbance is almost twice what solar radio
observations hinted at. The lack of SOHO data until just prior to the
arrival of the disturbance did not impart sufficient time to adjust
predictions prior to its arrival.

The CME impacted the Earth's magnetosphere near 20:01 UTC on 13
September, increasing the solar wind velocity from a quiet value near
350 km/sec to values in excess of 550 km/sec. At the present time, the
interplanetary magnetic field (IMF) is oriented in a near-neutral
configuration and might not contribute to significant intensification
of auroral storm activity unless it rotates into a more favorable
southward (negative) direction.

The middle latitude auroral activity watch has been activated,
effective immediately. The next 12 to 24 hours will be the most
volatile period.

This watch will remain valid through 18:00 UTC (2 pm EDT) on 16
September. It will then be allowed to expire. For updated
information, visit:
http://www.spacew.com/aurora/forum.html. For real-time plots of
current activity, visit: http://www.spacew.com/plots.html or
www.sec.noaa.gov.

PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO:
http://www.spacew.com/submitsighting.html


** End of Astroalert **

Dave