[SixClub] Solar flare X17.1

[W9FS - Jerry]

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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

07 September 2005

Solar Terrestrial Dispatch
www.spacew.com


INTENSE SOLAR FLARE PROMPTS WARNINGS

     A very strong class X17.1 solar flare exploded on the Sun at 17:40 UTC
(1:40 pm EDT). This is a significant event. Very few solar flares ever reach
the X-class rating, and far fewer ever exceed an X10 level. Only a few solar
flares each solar cycle (a 10-year period) exceed an X10 rating. An X17
solar
flare is 17 times more intense in x-rays than a class X1.0 (which is, by
itself, a very energetic event). This particular event was strong enough to
saturate one of the x-ray sensors on the GOES spacecraft and very nearly
saturated both sensors. This intense solar flare was visible in white-light
by observers at Holloman solar observatory in New Mexico.

     This event was associated with intense radio emissions and a strong
high-velocity coronal mass ejection that was ejected well to the southeast
of
the Earth. Despite the poor location of this event, there is a chance the
extreme western flanking edge of the associated shock wave may reach the
Earth sometime on 9 September. Prior to that time, energetic protons from
the
solar flare may begin reaching the Earth and result in an increase in the
radiation environment in the near-Earth space environment. Although no
significant geomagnetic or auroral storming is expected this time,
additional
possible major solar flares from this region during the next two weeks could
easily provide the impetus for very strong space weather storms.

     The sunspot complex responsible for this event is an old "friend," by
the name of Region 10798, which was responsible for producing periods of
severe geomagnetic storming last month. It's longevity is impressive, as
most
sunspot groups do not survive this long. As it came into view, NOAA assigned
a new number to this region. It will hereafter be known as Region 10808
(nick
named Region 808).

     The fact that this region has produced such a powerful flare suggests
that it contains a complex magnetic topology. It is just now coming into
view
around the eastern limb of the Sun and is still too close to the limb to
discern any significant detail. We expect additional major flares and
possibly additional significant major flares of X10 or greater intensities,
during the next week.

     Region 808 will gradually rotate across the solar disk during the next
two weeks. During that time, if it retains its volatility, it may produce
some serious effects at the Earth. The health of spacecraft may be
compromised if additional extreme events are observed. Power grids may
suffer
from induced currents caused by intense geomagnetic storms. Radio
communications may suffer from strong scintillation and absorption. And
large
regions of the Earth may be able to spot periods of auroral activity
("northern lights"). Region 808 will be best positioned to inflict strong
impacts on the Earth in approximately another 4 to 5 days, with maximal
effects possible from roughly 11 September through 18 September. Spacecraft
will remain vulnerable to potential strong space radiation storms through to
about 23 September.

     It is perhaps produnt to note that these strong solar flares pose no
known significant health threat to humans on the Earth. There is a greater
threat to human health for astronauts on the International Space Station,
but
even they are relatively well protected in the heavily shielded regions of
the space station. The combined effects of the Earth's magnetic field and
the
ionosphere protect human activities on Earth. However, some sensitive
industries on the ground can be adversely effected, including electrical
power generation facilities, ionospheric radio communications, satellite
communications, cellular phone networks, sensitive fabrication industries,
and others. During the next two weeks, these industries may see an increase
in anomalous incidents that may be attributed to space weather effects.


**  End of AstroAlert  **
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Regards,
The SIX METER WORLD WIDE CLUB team
Jerry W9FS
Six Club Director, SC# 66

Jerry N4AVM
Contest Director
(contests at 6mt.com)

Chris KC9CAU
Awards/Certificate Director
(awards at 6mt.com)