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From: oler@rho.uleth.ca (Cary Oler)
Reply-To: SOLAR-WARNINGS Distribution List <solar-warnings@lut.fi>
To: SOLAR-WARNINGS Distribution List <solar-warnings@lut.fi>
Message-Id: <9302062331.AA26614@rho.uleth.ca>
Subject: ALERT: Major Solar Flare Alert - 06 Feb
Date: Sat, 6 Feb 93 16:31:43 MST
X-Sequence: 83
X-Charset: FI
X-Char-Esc: 29
Status: OR

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                           MAJOR SOLAR FLARE ALERT

                        ISSUED: 23:00 UT, 06 FEBRUARY

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                     * Low to Moderate Impact Possible *


MAJOR ENERGETIC EVENT SUMMARY:

            ( All times are valid for the UT day of 06 February )

Flare Size: Class M9.6/3B
  Location: N13E25 (Region 7417)
  Tenflare: 660 sfu.  Duration: 15 minutes.
SESC Times: Begin=06/1814 UT, Peak=06/1824 UT, End=06/1841 UT
            (SESC Times are based on a half-power-point system)
    Sweeps: No Sweeps Observed


PRELIMINARY X-RAY TIME PROFILE DATA AND ESTIMATED STATISTICS:

BEGIN (XRAY)   MAX  (XRAY)   END  (XRAY)   DURATION   INTEG. FLUX   SWF DUR.
------------   -----------   -----------   --------   -----------   --------
 1814 (C1.5)   1824 (M9.6)   1916 (C9.9)   062 MIN.   0.135 J/m^2    058 min

NOTE:  The xray time profile data above is not based on the half-power-point
       system, but is intended to give a general idea of the duration of the
       entire event, from the start to the end when xrays fall below M-class
       levels.  Integrated x-ray flux covers the interval from start to end.


SYNOPSIS:

     This major flare erupted out of Region 7417 (at N13E25).  It narrowly
     missed becoming an X-class event and had a typical rapid-rise and slow
     decay x-ray signature.  The event was large in optical extent (3B),
     although this is not surprising given the size of the region is near
     1000 millionths.  No Type II or IV sweeps have yet been reported from
     this flare.  The flare appears to have been associated with a
     simultaneous 2B event in Region 7419 at N11E25.  Interaction between
     these two regions may have been responsible for this event.  Some
     interesting post-flare near-sinusoidal x-ray oscillations were observed
     following this flare and are continuing in progress at the time of this
     writing.  The oscillations measure approximately 15 minutes in duration.
     Consult the x-ray file "930206x1.gif" on the anonymous FTP site:
     xi.uleth.ca (IP number 142.66.3.29) in the directory "pub/solar/Xrays"
     for a high-resolution copy of these oscillations.  The file will become
     available near 24:00 UT on 06 February.

          Good potential for future major flare activity exists from this
     region.  Interaction between Regions 7417 and 7419 may provide the
     necessary triggers for future major activity.  Although no protons are
     expected from this particular event, future proton flaring is not out of
     the question.  Additional minor to major flares are expected (M to
     X-class in nature).

          There is a moderate risk for proton injections by possible future
     major flares.  For 3-hour updated x-ray flare data (and plots), issue
     the Internet command: FINGER SOLAR@XI.ULETH.CA.


POTENTIAL TERRESTRIAL IMPACT ASSESSMENT:

     The following tables depict the preliminary estimated potential for
terrestrial impacts in various categories.  These tables are valid only for
the flare described and do not include assessments for previous influential
flare events.


                      ----------------------------------
                      POTENTIAL MAGNITUDE OF DISTURBANCE
                      ----------------------------------
                                 HIGH : 05 %
                             MODERATE : 10 %
                                  LOW : 40 %
                                 NONE : 45 %
                      ----------------------------------
                      OVERALL ARRIVAL PROBABILITY : 40 %


                      ESTIMATED WINDOW OF SHOCK ARRIVAL
    ---------------------------------------------------------------------
   |  MINIMUM   |    EARLY     |  PREFERRED  |     LATE     |  MAXIMUM   |
   |------------|--------------|-------------|--------------|------------|
   | 08/0200 UT |  08/0800 UT  | 08/2000 UT  |  09/0600 UT  | 09/1600 UT |
   |  FEBRUARY  |   FEBRUARY   |  FEBRUARY   |   FEBRUARY   |  FEBRUARY  |
   |------------|---------------------|---------------------|------------|
   |     5 %    |  45%  PROBABILITY   |  45% PROBABILITY    |     5 %    |
    ---------------------------------------------------------------------


---------------------------------       ----------------------------------
  POTENTIAL FOR >10 MEV PROTONS           POTENTIAL FOR >100 MEV PROTONS
---------------------------------       ----------------------------------
    HIGH FLUX :  1 %  > 100 PFU             HIGH FLUX :  0 %  > 100 PFU
MODERATE FLUX :  5 %  >  10 PFU         MODERATE FLUX :  0 %  >  10 PFU
     LOW FLUX : 30 %  >   1 PFU              LOW FLUX :  1 %  >   1 PFU
         NONE : 64 %  <=  1 PFU                  NONE : 99 %  <=  1 PFU
----------------------------------      ----------------------------------
OVERALL ARRIVAL PROBABILITY: 20 %       OVERALL ARRIVAL PROBABILITY: 1 %

---------------------------------       ---------------------------------
EST. POTENTIAL GEOMAGNETIC IMPACT       EST. POTENTIAL IONOSPHERIC IMPACT
---------------------------------       ---------------------------------
       SEVERE STORM :  5 %                 LOW LATITUDES : NIL
        MAJOR STORM : 10 %              MIDDLE LATITUDES : NIL - MINOR
        MINOR STORM : 35 %                HIGH LATITUDES : NIL - MINOR
     ACTIVE OR LESS : 50 %               POLAR LATITUDES : NIL - MINOR
---------------------------------       ---------------------------------
 PROBABLE SI ASSOCIATION : 40 %       ESTIMATED GLOBAL IMPACT: NIL - MINOR


ESTIMATED POTENTIAL DURATION OF DISTURBANCE AFTER ARRIVAL: NIL TO 24 HOURS

EST. PROBABILITY FOR GEOSYNCHRONOUS SATELLITE MAGNETOPAUSE CROSSINGS:  25 %


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