From: oler@rho.uleth.ca (Cary Oler)
Subject: ALERT: Major Solar Flare Alert
Apparently-To: sci-space-news@ames.arc.nasa.gov
Followup-To: sci.space
Organization: University of Lethbridge
Date: Mon, 7 Sep 1992 21:36:10 GMT

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                           MAJOR SOLAR FLARE ALERT

                        ISSUED: 20:50 UT, 07 SEPTEMBER

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                       *  NIL to Low Impact Possible  *

PLEASE NOTE:  DUE TO SYSTEM PROBLEMS EXPERIENCED OVER THE WEEKEND, THE
              PREVIOUS MAJOR FLARE ALERTS COULD NOT BE DISPATCHED.


MAJOR ENERGETIC EVENT SUMMARY:

            ( All times are valid for the UT day of 07 September )

Flare Size: Class M5.7/2B
  Location: S10W53 (Region 7270)
  Tenflare: None reported.
SESC Times: Begin=07/1925 UT, Peak=07/1941 UT, End=07/1955 UT
            (SESC Times are based on a half-power-point system)
    Sweeps: No Type II reported.
            No Type IV reported.


PRELIMINARY X-RAY TIME PROFILE DATA AND ESTIMATED STATISTICS:

BEGIN (XRAY)   MAX  (XRAY)   END  (XRAY)   DURATION   INTEG. FLUX   SWF DUR.
------------   -----------   -----------   --------   -----------   --------
 1926 (C2.2)   1941 (M5.7)   2045 (C9.8)   078 MIN.   0.115 J/m^2    071 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 event was not as substantial as the previous X-class flares
     from Region 7270.  No notable radio or sweep frequency events have been
     reported with this flare.  The strong levels of flaring from this group
     are expected to continue, but should begin to subside over the next 48
     to 72 hours.  Additional major M and/or X-class flares are possible from
     this group before it departs the west limb.

     There is a moderate probability that the previous major flare events
     (most notable, the X1.7/2B tenflare at 18:52 UT on 06 September) will
     generate interplanetary disturbances capable of producing minor
     terrestrial impacts.  Levels of geomagnetic activity are expected to
     become active to minor storm on 08 September in response to the recent
     high levels of flare activity from Region 7270.  Activity could remain
     unstable for several days thereafter.


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 :  0 %
                             MODERATE :  5 %
                                  LOW : 25 %
                                 NONE : 70 %
                      ----------------------------------
                      OVERALL ARRIVAL PROBABILITY : 35 %


                      ESTIMATED WINDOW OF SHOCK ARRIVAL
    ---------------------------------------------------------------------
   |  MINIMUM   |    EARLY     |  PREFERRED  |     LATE     |  MAXIMUM   |
   |------------|--------------|-------------|--------------|------------|
   | --/---- UT |  --/---- UT  | --/---- UT  |  --/---- UT  | --/---- UT |
   |  SEPTEMBER |   SEPTEMBER  |  SEPTEMBER  |  SEPTEMBER   |  SEPTEMBER |
   |------------|---------------------|---------------------|------------|
   |     5 %    |  45%  PROBABILITY   |  45% PROBABILITY    |     5 %    |
    ---------------------------------------------------------------------
       A SHOCK IS NOT EXPECTED FROM THIS EVENT OR WILL BE INSIGNIFICANT


---------------------------------       ----------------------------------
  POTENTIAL FOR >10 MEV PROTONS           POTENTIAL FOR >100 MEV PROTONS
---------------------------------       ----------------------------------
    HIGH FLUX :  0 %  > 100 PFU             HIGH FLUX :  0 %  > 100 PFU
MODERATE FLUX :  0 %  >  10 PFU         MODERATE FLUX :  0 %  >  10 PFU
     LOW FLUX : 10 %  >   1 PFU              LOW FLUX :  0 %  >   1 PFU
         NONE : 90 %  <=  1 PFU                  NONE :100 %  <=  1 PFU
----------------------------------      ----------------------------------


---------------------------------       ---------------------------------
EST. POTENTIAL GEOMAGNETIC IMPACT       EST. POTENTIAL IONOSPHERIC IMPACT
---------------------------------       ---------------------------------
       SEVERE STORM :  0 %                 LOW LATITUDES : NONE
        MAJOR STORM :  5 %              MIDDLE LATITUDES : NONE
        MINOR STORM : 20 %                HIGH LATITUDES : MINOR
     ACTIVE OR LESS : 75 %               POLAR LATITUDES : MINOR
---------------------------------       ---------------------------------
 PROBABLE SI ASSOCIATION : 35 %       ESTIMATED GLOBAL IMPACT: NONE - MINOR


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

EST. PROBABILITY FOR GEOSYNCHRONOUS SATELLITE MAGNETOPAUSE CROSSINGS:  10 %


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