From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Oct 29 2003 - 06:37:37 PST
----- Original Message -----
From: Cary Oler
Sent: Wednesday, October 29, 2003 1:06 AM
To: sun-earth_at_SkyandTelescope.com
Subject: AstroAlert: *INTENSE* CLASS X17+ SOLAR FLARE OBSERVED !
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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
28 October 2003
* INTENSE CLASS X17 SOLAR FLARE OBSERVED!
* MIDDLE LATITUDE AURORAL ACTIVITY WARNING ISSUED
* LOW LATITUDE AURORAL ACTIVITY WATCH ISSUED
PLEASE NOTE: Our web site (all space weather web sites) are seeing
significant levels of traffic and will be slow to respond. Please be patient.
INTENSE CLASS X17 SOLAR FLARE OBSERVED!
At 04:35 UTC on 28 October (11:35 pm EST on 27 October), Solar Terrestrial
Dispatch issued a warning of a possible imminent X-class flare from Region
486. Commencing at 09:51 UTC (4:51 am EST on 28 October), one of the largest
solar flares this solar cycle blew out of Region 486. Solar flares can come
larger, but not by much. Events up to approximately twice the strength of
todays flare are possible. Nevertheless, this event had bulging muscles and
has great potential for producing significant displays of auroral activity
("Northern Lights") TONIGHT and TOMMORROW night, with heavier preference on
TONIGHT.
The solar flare reached a class X17.2 intensity at an x-ray wavelength
between 1 and 8 Angstroms. That is over 1,700 times more powerful than your
regular every-day run-of-the-mill C-class x-ray flares and it is over 34
times more powerful than the lowest-category major solar flare. X-rays from
this flare reached a maximum intensity at 11:10 UTC on 28 October.
X-rays were so intense that on the day-side of the Earth (over Europe),
ionospheric currents formed that caused the Earth's magnetic field to dip a
little bit in strength. Known as a magnetic crochet, these events are
detected by magnetometers and are typically only observed during very intense
solar flares.
Invisible to all instruments, this solar flare had accelerated protons to
extremely high energies and beamed them toward the Earth. Ten minutes after
x-rays had reached their maximum intensity, the blast of energetic protons
began flooding the Earth's space environment and bombarding the Earth's
protective ionosphere. Not to worry though. Our ionosphere can easily handle
the onslaught. Protons with energies well in excess of 100 MeV have been
observed. In fact, the influx of energetic protons was so intense that they
produced secondary reactions within the ionosphere that could be observed by
neutron monitors at ground-level in the arctic regions. These "Ground Level
Events" (or GLEs) are symptoms of an intense space radiation storm. In fact,
before this space radiation storm ends, there is a chance radiation levels
could surpass category S4 levels (on a scale between S1 and S5). There are
usually only about 3 radiation storms per solar cycle (~11 years) that reach
that intensity.
Didier Van Hellemont reported that the members of an astronomical observatory
in Belgium were testing their camera during the morning and fortuitously
caught the elusive and rare white-light component of this flare on video! A
frame of the video containing the white-light flare is visible at:
http://www.urania.be/php-txt/dynpage/URANIA_solarflare.jpg
While observing the Sun using a small reflector telescope in Germany, Peter
Kuklok is also said to have observed the white-light component of this flare
within the penumbral area of Region 486.
We extend our congratulations to these individuals and groups! It is an
extraordinary feat to catch a white-light flare in progress! White-light
flares are only observed during the most intense solar flares - and then only
for a brief period of time.
So what can we expect from this solar flare? If we're lucky, perhaps a really
good light show TONIGHT in the heavens above.
The coronal mass ejection associated with this major flare was directed
squarely at the Earth. A near perfect halo coronal mass ejection rapidly
formed. When the velocity of this CME was measured from images taken by the
LASCO coronagraph, jaws dropped. The velocity of the disturbance in the plane
of the sky was measured by SOHO scientists to be near 2,125 kilometers per
second. At that velocity, the disturbance could reach the Earth within 19
hours. However, they do decelerate as they expand outward and this
deceleration increases the time it takes them to reach the Earth.
Even accounting for this delay (which is hard to predict), there is a good
chance this disturbance could reach the Earth in the early to mid morning UTC
hours of 29 October.
For North Americans, this translates to a time of arrival sometime around 3
am Eastern Standard Time or near midnight on the west coast TONIGHT. If the
disturbance does not arrive until later, North America's best chance to see
auroral activity will come tommorrow night (Wednesday night, 29 October).
PLEASE REMEMBER that there is also a chance this disturbance might produce
very little Northern Lights activity. Whether it does or doesn't depends on
the internal magnetic field configuration of the disturbance. If it produces
storming, it will probably produce STRONG storming. Otherwise, it might not
much.
Be patient, watch conditions, and/or stay informed. If you are under cloudy
skies and have never seen aurora before, this might be an event worth
consdering taking a drive for.
A MIDDLE LATITUDE AURORAL ACTIVITY WARNING and a LOW LATITUDE AURORAL
ACTIVITY WATCH have been issued for the UTC day of 29 and 30 October, but
with heaviest emphasis on 29 October. The middle latitude warning is appended
below. The low latitude watch is identical except that the "Overall
opportunity" for observing auroral activity from the low latitudes is
considered "Fair to Poor" (which is remarkably good!).
Good luck to everyone!
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
MIDDLE LATITUDE AURORAL ACTIVITY WARNING
WARNING ISSUED: 20:00 UTC, 28 OCTOBER 2003
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
VALID BEGINNING AT: 00:00 UTC 29 OCTOBER 2003
VALID UNTIL: 23:00 UTC (7 pm EDT) ON 30 OCTOBER
HIGH RISK PERIOD: 29 OCTOBER (UTC DAYS)
MODERATE RISK PERIOD: 28 - 30 OCTOBER
PREDICTED ACTIVITY INDICES: 20, 70, 40, 20 (28 OCTOBER - 31 OCTOBER)
POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: HIGH
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: NIL TO LOW
OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: GOOD
AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
(THIS LINE IS VALID *ONLY* IF FAVORABLE STORM CONDITIONS OCCUR)
CENTRAL CALIFORNIA TO NEVADA TO SOUTHERN UTAH TO NORTHERN NEW MEXICO TO
NORTHERN TEXAS TO OKLAHOMA TO ARKANSAS TO NORTHERN MISSISSIPPI TO NORTHERN
ALABAMA TO NORTHERN GEORGIA TO SOUTH CAROLINA.
ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...
(THIS LINE IS VALID *ONLY* IF FAVORABLE STORM CONDITIONS OCCUR)
SOUTHERN FRANCE TO NORTHERN ITALY TO AUSTRIA TO HUNGARY TO UKRAINE TO
CENTRAL AND SOUTHERN RUSSIA.
NEW ZEALAND AND SOUTHERN REGIONS OF AUSTRALIA MAY ALSO OBSERVE PERIODS OF
POTENTIALLY STRONG ACTIVITY.
SYNOPSIS...
FIRST, a large caveat: A strong auroral storm may happen, or it may not.
Whether it does or does not depends on conditions inside the disturbance and
how it couples with the Earth's magnetic field. If conditions are favorable,
very strong storm activity may be possible. If conditions are not favorable,
there may be no visible auroral activity in sight. The POTENTIAL for
observing activity with this disturbance is about as high as you can ask.
Nevertheless, if the configuration of the disturbance is not favorable for
coupling with the Earth, nothing will happen.
This is without question, one of the most significant space weather
disturbances of the current 11-year solar cycle. It was associated with a
historic class X17.2 solar x-ray flare on 28 October and a high velocity
coronal mass ejection that is directed squarely at the Earth. The potential
exists for a significant space weather storm should this disturbance contain
favorable characteristics.
A middle latitude auroral activity WARNING means that conditions are
expected to become favorable for observing auroral activity over widespread
middle latitude regions. A LOW LATITUDE auroral activity WATCH is also being
issued for this event.
The disturbance is expected to impact sometime in the early to mid UTC
hours of 29 October. For North American observers, this means activity could
occur TONIGHT - LATE TONIGHT and for most regions sometime AFTER MIDNIGHT
(perhaps in the hours around or after 3 am EST).
This warning will remain valid through 23:00 UTC (7 pm EDT) on
30 October. It will then be updated, downgraded to a watch or allowed to
expire altogether. 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
PLEASE REPORT VALID OBSERVATIONS OF AURORAL ACTIVITY TO:
http://www.spacew.com/submitsighting.html
** End of the AstroAlert Bulletin **
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