A s t r o A l e r t
Sun-Earth Alert
Solar Terrestrial Dispatch
http://www.spacew.com
11 August 2001
MIDDLE LATITUDE AURORAL ACTIVITY WATCH
An impressive eruption was observed on the Sun just west of the central
solar meridian between around 09:00 and 16:00 UTC on 09 August (5 am and
noon
EDT on 09 August). This event appears to have been correlated with a partial
halo coronal mass ejection that was observed accelerating out of the corona
at velocities near or in excess of about 512 kilometers per second (1.8
million kilometers per hour or about 1.15 million miles per hour).
There is also a suspected high velocity solar wind stream enroute to
the
Earth emanating from a well placed and recurrent solar coronal hole. These
two disturbances may impact the Earth's magnetosphere and produce periods of
enhanced auroral activity on 12 and 13 August.
This is an interesting period of time for sky watchers as the Perseids
meteor shower is also expected to peak on 12 August. If things turn out as
forecasters believe they might, sky watchers may very well be treated to
periods of visible auroral activity combined with occasional Perseid meteor
activity.
Observers in North America (particularly central and northern regions
of
the U.S. states) are encouraged to begin watching for signs of increased
auroral activity during the late evening hours of 11 August and the early
morning hours of 12 August, although the bulk of the auroral activity
probably won't occur until a bit later and on the evening/morning of 12/13
August for North America.
The potential for auroral activity will linger through 13 and perhaps
the early part of 14 August before decaying back to quieter conditions. A
middle latitude auroral activity watch has been issued for middle latitude
dark-sky locations for the UTC days of 12 through 13 August and part of 14
August. A copy of the watch bulletin is included below.
A quick an easy link to current information and forecasts may be found
by going to: http://www.spacew.com/aurora/forum.html
Information and movies pertaining to the coronal mass ejection and
eruptive solar activity of 09 August may be found at:
ftp://ares.nrl.navy.mil/pub/lasco/halo/20010809
Observers who spot auroral activity are encouraged to report their
sightings as soon as possible to the Global Auroral Activity Sighting
Network
by posting sightings using the form at:
PLEASE REPORT SIGHTINGS HERE: http://www.spacew.com/www/subaurora.html
Near-realtime lists of auroral activity sightings from this network may
be read by going to: http://www.spacew.com/www/auroras.html
A forum of knowledgable and experienced auroral activity observers from
around the world is available at: http://www.spacew.com/aurora/forum.html.
Sightings of activity are also often posted here in near-realtime. However,
in order for sightings to be permanently archived into a scientifically
feasible database, observers must report sightings to the appropriate URL:
http://www.spacew.com/www/subaurora.html
Real-time discussions and updates of current activity are possible
through a private IRC network. Information on how to join is available at:
http://www.spacew.com/irc
///////////////////////\
MIDDLE LATITUDE AURORAL ACTIVITY WATCH
WATCH ISSUED: 20:10 UTC, 10 AUGUST 2001
///////////////////////\
VALID BEGINNING AT: 06:00 UTC ON 12 AUGUST (2:00 am EDT, 12 August)
VALID UNTIL: 19:00 UTC ON 14 AUGUST (3 pm EDT, 14 August)
HIGH RISK PERIOD: 12 - 13 AUG (UTC DAYS)
MODERATE RISK PERIOD: 12 - 14 AUG
PREDICTED ACTIVITY INDICES: 10, 40, 30, 14 (11 AUG - 14 AUG)
POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE
POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 18 TO 24 HOURS
MINOR BELT = 24 TO 48 HOURS
ESTIMATED OPTIMUM OBSERVING CONDITIONS: NEAR LOCAL MIDNIGHT
EXPECTED LUNAR INTERFERENCE: NIL, BECOMING MODERATE AFTER MOONRISE
OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR
AURORAL ACTIVITY MAY BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
NORTHERN WASHINGTON STATE TO NORTHERN WYOMING TO SOUTH DAKOTA TO
SOUTHERN MINNESOTA TO WISCONSIN TO SOUTHERN MICHIGAN TO NORTHERN
PENNSYLVANIA TO NORTHERN NEW JERSEY.
ACTIVITY MAY ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
NORTHERN UNITED KINGDOM TO EXTREME NORTHERN DENMARK TO SOUTHERN FINLAND
TO NORTHERN RUSSIA. REGIONS OF SOUTHERN NEW ZEALAND MAY SPOT PERIODS OF
ACTIVITY.
SYNOPSIS...
An interesting partial halo coronal mass ejection that may have been
associated with a solar filament channel eruption near 10:30 UTC on 09
August
may intensify levels of auroral activity on 12 and 13 August. Auroral
activity may be further invigorated by the anticipated arrival of a high
velocity solar wind stream emanating from a recurrent solar coronal hole.
The
combined effects could produce periods of moderately strong auroral activity
over high and some dark-sky middle latitude regions on 12 and 13 August,
with
particular emphasis on the UTC day of 12 August. Combined with the Perseids
meteor shower, expected to peak on the UTC day of 12 August (evening of the
11th and morning of the 12th for North American observers), the sky may
hold an interesting variety of activity.
This watch will remain in effect until 19:00 UTC on 14 August when it
will either be allowed to expire or will be updated.
PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO:
http://solar.spacew.com/www/auroras.html
- OR *
Use the STD AURORA MONITOR Software to monitor conditions and
report sightings. It is available at:
WE HAVE A DISCUSSION FORUM FOR AURORA ENTHUSIASTS AVAILABLE AT:
http://www.spacew.com/aurora/forum.html
** End of AstroAlert **
In Spirit, Leslee
The only thing necessary for the triumph of evil is for good men to do nothing.
...........Edmund Burke