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From: oler@rho.uleth.ca (Cary Oler)
Message-Id: <9306241607.AA25597@rho.uleth.ca>
Subject: ALERT: MAJOR SOLAR FLARE ALERT - SUSPECTED PROTON FLARE
To: solar-warnings@lut.fi
Date: Thu, 24 Jun 93 10:07:12 MDT
X-Mailer: ELM [version 2.3 PL11]
Reply-To: SOLAR-WARNINGS Distribution List <solar-warnings@lut.fi>
X-Sequence: 129
Status: OR

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                           MAJOR SOLAR FLARE ALERT

                          ISSUED: 14:00 UT, 24 JUNE

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                        * NIL to Low Impact Possible *


MAJOR ENERGETIC EVENT SUMMARY:

              ( All times are valid for the UT day of 24 June )

Flare Size: Class M9.7/1N
  Location: S11E64 (Region 7529)
  Tenflare: 390 sfu at 0722 UT.
SESC Times: Begin=24/0716 UT, Peak=24/0735 UT, End=24/0752 UT
            (SESC Times are based on a half-power-point system)
    Sweeps: Type II (Importance 3).
                  Estimated shock velocity: 2500 km/sec.
                  Begin: 0729 - 0736 UT.
            Type IV (Importance 3).
                  Begin: 0659 - 0900 UT.
   Protons: Proton enhancement expected over next 24 hours.  Possible event.


PRELIMINARY X-RAY TIME PROFILE DATA AND ESTIMATED STATISTICS:

BEGIN (XRAY)   MAX  (XRAY)   END  (XRAY)   DURATION   INTEG. FLUX   SWF DUR.
------------   -----------   -----------   --------   -----------   --------
 0640 (B4.7)   0736 (M9.7)   0830 (C9.8)   110 MIN.   0.154 J/m^2    062 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:

     Region 7529 spawned a major class M9.7/2B tenflare from S11E64 at
     07:35 UTC.  It was accompanied by major Types II and IV sweeps.
     The estimated shock velocity of the Type II was 2,500 km/sec.
     The x-rays from this region have shown impressive surges with
     long-decay signatures throughout the last 24 hours.  The flare
     itself was similarly long in duration and had an impressive LDE
     signature.  The region has not been magnetically imaged to
     provide us with any quantitative information regarding shear
     levels or magnetic configurations.  However, it will be closely
     scrutinized today.  When it rotated into view yesterday, the
     region did not appear to be capable of producing large flares.
     X-ray imagery of this region was relatively dim.  Likewise, it
     was not associated with any strong limb emissions (Ca XV or Fe
     emissions).  But today, imagery is showing strong x-ray emissions
     from this region.

     There is another region rotating into view behind Region 7529.
     It might possibly be old Region 7518.  A bright surge was
     reported in the area of this new region.

     Additional major flares are likely from Region 7529.


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 : 30 %
                                 NONE : 55 %
                      ----------------------------------
                      OVERALL ARRIVAL PROBABILITY : 30 %


              ESTIMATED WINDOW OF SHOCK ARRIVAL IF SHOCK ARRIVES
    ---------------------------------------------------------------------
   |  MINIMUM   |    EARLY     |  PREFERRED  |     LATE     |  MAXIMUM   |
   |------------|--------------|-------------|--------------|------------|
   | 25/2300 UT |  26/0300 UT  | 26/0900 UT  |  26/1400 UT  | 26/1900 UT |
   |    JUNE    |     JUNE     |    JUNE     |     JUNE     |    JUNE    |
   |------------|---------------------|---------------------|------------|
   |    10 %    |  40%  PROBABILITY   |  40% PROBABILITY    |    10 %    |
    ---------------------------------------------------------------------
                           (Preliminary Estimates)


---------------------------------       ----------------------------------
  POTENTIAL FOR >10 MEV PROTONS           POTENTIAL FOR >100 MEV PROTONS
---------------------------------       ----------------------------------
    HIGH FLUX :  5 %  > 100 PFU             HIGH FLUX :  0 %  > 100 PFU
MODERATE FLUX : 45 %  >  10 PFU         MODERATE FLUX :  0 %  >  10 PFU
     LOW FLUX : 30 %  >   1 PFU              LOW FLUX :  1 %  >   1 PFU
         NONE : 20 %  <=  1 PFU                  NONE : 99 %  <=  1 PFU
----------------------------------      ----------------------------------
OVERALL ARRIVAL PROBABILITY: 50 %       OVERALL ARRIVAL PROBABILITY:  1 %

---------------------------------       ---------------------------------
EST. POTENTIAL GEOMAGNETIC IMPACT       EST. POTENTIAL IONOSPHERIC IMPACT
---------------------------------       ---------------------------------
       SEVERE STORM : 05 %                 LOW LATITUDES : MINOR
        MAJOR STORM : 10 %              MIDDLE LATITUDES : MINOR
        MINOR STORM : 30 %                HIGH LATITUDES : MINOR
     ACTIVE OR LESS : 55 %               POLAR LATITUDES : MINOR
---------------------------------       ---------------------------------
 PROBABLE SI ASSOCIATION : 75 %       ESTIMATED GLOBAL IMPACT: MINOR - MAJOR

ESTIMATED PRELIMINARY FORECAST PEAK PLANETARY A-INDEX: 27

ESTIMATED POTENTIAL DURATION OF DISTURBANCE IF IT ARRIVES: 24 TO 36 HOURS

EST. PROBABILITY FOR GEOSYNCHRONOUS SATELLITE MAGNETOPAUSE CROSSINGS:  40%


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