[AZ-Observing] Major Solar Flare; Possible Aurora Tonight
- From: BillFerris@xxxxxxx
- To: az-observing@xxxxxxxxxxxxx
- Date: Tue, 28 Oct 2003 16:22:22 -0500
I'm sending this to the list a second time because it hasn't appeared in the
45-minutes since the original message was sent:
==============
From Spaceweather.com:
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** ALERT -- EXCEPTIONAL X18 FLARE **
An exceptionally intense class X18 solar x-ray flare has been observed from
Region 486. It has produced a prompt high-energy proton event in space and is
associated with a strong full-halo coronal mass ejection (directed heavily
Earthward). This solar flare ranks as one of the largest of this solar cycle.
It will produce a potentially strong impact at the Earth within 48 hours or
less. The predicted arrival time has not yet been computed. Additional data and
analysis are first necessary. Please allow us several hours to update our CME
impact prediction web page.
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...and here's the updated forecast:
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Event #49 - 28 October 2003
Issued: 16:30 UTC, 28 October 2003
SOURCE EVENT
Class X17.2 Flare in Region 486 at 11:10 UTC on 28 October 2003
Type II: 1250 km/sec
Estimated LASCO-derived Plane of Sky Velocity: 2125 km/sec
ESTIMATED TIME OF ARRIVAL OF SHOCK AT EARTH
Estimated Impact Window: 00:00 UTC on 29 October to 21:00 UTC on 29 October
Preferred Predicted Impact Time: 08:00 UTC, 29 October 2003 (3 am EST on 29
October)
Estimated Shock Strength (0=Weakest, 9=Strongest): 9
Predicted Behavior of IMF at Shock Impact
At Shock Impact, the Interplanetary Magnetic Field is predicted to initially
turn:
SOUTHWARD
IMPORTANT TIME OF ARRIVAL NOTICE FOR NORTH AMERICANS
The preferred time of arrival is ***TONIGHT***, TUESDAY NIGHT (before you go to
bed that night) near or after 3 am Eastern Standard Time).
That's 2 am Central Standard Time on TONIGHT.
That's 1 am Mountain Standard Time on TONIGHT.
That's MIDNIGHT Pacific Standard Time on TONIGHT.
EXPECT RESIDUAL ACTIVITY (LESS INTENSE) TOMMORROW NIGHT (WEDNESDAY, 29 OCT) AS
WELL !
EVENT #49 NOTES:
This is the most energetic Earthward-directed event of the solar cycle.
SEVERE to MAJOR geomagnetic storming is expected to abruptly commence following
the arrival of the shock front from this flare.
This flare was associated with a Ground-Level Event. It was also associated
with very high energy protons at greater than 100 MeV (which are still
climbing, over 5 hours after the event began). A magnetic crochet was observed
over the daylit sections of the ionosphere. An exceptionally intense shortwave
fadeout and polar cap absorption event are in progress. There are reports this
event was observed in white-light. Intense radio bursts were associated with
this event across the spectrum. The type II shock velocity is not
representative of the observed velocity of this CME. The observed velocity as
determined by SOHO was 2125 km/sec.
This event has the potential to produce the strongest geomagnetic storm since
1989. Auroral activity could become visible into the deep low latitude regions.
This one is worth driving a good long distance over to find clear skies. It has
better potential to produce low-latitude aurora than almost any other event
observed in the past decade. Keep in mind that it is also possible the
disturbance may not be nearly as geoeffective as many would like. It all
depends on the character of the magnetic fields imbedded within the coronal
mass ejection. However, we believe it will either be very large, or only
modestly large in terms of its capacity to produce disturbed geomagnetic and
auroral activity. We do not expect this disturbance to be small.
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Regards,
Bill
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