From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Nov 06 2003 - 06:43:49 PST
----- Original Message -----
From: Cary Oler
Sent: Wednesday, November 05, 2003 11:43 PM
To: sun-earth_at_SkyandTelescope.com
Subject: AstroAlert: A Record-Breaking Solar Flare!
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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
Images and Movies of this event are available at:
http://www.spacew.com/astroalert.html
05 November 2003
A RECORD-BREAKING SOLAR FLARE & MID-LATITUDE AURORA WATCH
At approximately 19:47 UTC (2:47 pm EST) on 04 November, active sunspot
complex 10486 spawned what is probably the most intense x-ray flare in
history. X-ray sensors on-board the GOES spacecraft are only capable of
registering x-ray intensities up to a class X17.4 level. X-ray intensities
beyond this level saturate the detectors. This solar flare saturated the
x-ray detectors for 11 minutes, leaving space weather forecasters and
scientists with some work to try and extrapolate the true intensity of the
event. Based on a preliminary extrapolation, it appears that this x-ray flare
peaked somewhere between the X30 and X40 levels, which was unheard of until
yesterday and is possibly as much as twice as energetic as the X17 solar
flare observed on 02 November.
To place this event into historic perspective, it very likely ranks as
the most powerful x-ray flare ever observed. During the last two weeks,
active Region 10486 has produced three x-ray flares that have ranked within
the top 10 of the most intense events in history. It has been quite a ride!
Region 10486 has now rotated behind the western limb and out of view. It
will now spend the next two weeks traversing the far side of the Sun. Whether
it survives its passage on the far-side and returns to the eastern limb in
two weeks in a form still capable of producing energetic events remains
unknown. It is possible it could return in a form still capable of producing
energetic events, but the odds are against it.
Although only time will tell, observers on Earth will be able to monitor
its progress indirectly by watching for coronal mass ejections that occur on
the far side of the Sun, but are still visible from Earth via the SOHO LASCO
cameras.
Spectacular imagery of this solar flare and the associated high velocity
coronal mass ejection are available from the SOHO web site:
http://soho.nascom.nasa.gov/hotshots
A movie of the event in the light of hydrogen is also available from:
http://www.spacew.com/x30ha.gif
It is known that yesterdays remarkable solar flare was associated with a
coronal mass ejection. The vast majority of mass thrown out was directed well
to the west of the Earth. However, a small portion was also directed
Earthward. That portion is expected to impact the Earth on 06 November. After
the disturbance arrives, it may be capable of producing periods of minor to
major geomagnetic and auroral storm activity. A disturbance as large as was
observed on 29 and 30 October is not expected. Nevertheless, auroral activity
could become visible from many middle latitude locations. A middle latitude
aurora watch is active for 06 November. For North Americans, that is TONIGHT.
Late tonight, near or after local midnight. Interference from the near-full
moon will hamper attempts to view activity.
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
MIDDLE LATITUDE AURORAL ACTIVITY WATCH
WATCH ISSUED: 20:15 UTC, 05 NOVEMBER 2003
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VALID BEGINNING AT: 00:00 UTC ON 06 NOVEMBER
VALID UNTIL: 23:00 UTC (7 pm EDT) ON 07 NOVEMBER
PREDICTED IMPACT TIME OF DISTURBANCE:
APPROX. 07:00 UTC ON 06 NOVEMBER, +/- AT LEAST SEVERAL HOURS SEVERAL
HIGH RISK PERIOD: 06 NOVEMBER (UTC DAYS)
MODERATE RISK PERIOD: 06 - 07 NOVEMBER
PREDICTED ACTIVITY INDICES: 12, 35, 20, 15 (05 NOVEMBER - 08 NOVEMBER)
POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE
POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 06 TO 12 HOURS
MINOR BELT = 12 TO 18 HOURS
ESTIMATED OPTIMUM OBSERVING CONDITIONS: NEAR AND AFTER LOCAL MIDNIGHT
EXPECTED LUNAR INTERFERENCE: MODERATE
OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR TO GOOD
AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
NORTHERN OREGON TO NORTHERN WYOMING TO SOUTH DAKOTA TO SOUTHERN MINNESOTA
TO WISCONSIN TO MIGHIGAN TO NEW YORK STATE TO NEW HAMPSHIRE.
ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
IRELAND TO CENTRAL UNITED KINGDOM TO EXTREME NORTHERN NETHERLANDS TO
EXTREME NORTHERN GERMANY TO SOUTHERN SWEDEN TO SOUTHERN FINLAND TO
NORTHERN RUSSIA.
ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY SOUTH OF A LINE FROM...
NEW ZEALAND AND EXTREME SOUTHEASTERN AUSTRALIA.
SYNOPSIS...
Effects of perhaps the largest x-ray solar flare on record are expected
to impact the Earth sometime near 07:00 UTC on 06 November, give or take
several hours. The solar flare occurred on the western limb of the Sun and as
a result is not expected to produce significant effects at the Earth.
However, the disturbance should have the strength to produce periods of
auroral storming over the high and middle latitude regions.
This watch will remain valid through 23:00 UTC (7 pm EDT) on
07 November. It will then be updated or allowed to expire. Most (if not all)
of the activity is expected to occur within the first 6 to 12 hours after the
disturbance impacts. For this reason, we don't expect very much on 07
November. 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 the AstroAlert Bulletin **
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