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Subject: SPACE Digest V13 #266

SPACE Digest                                     Volume 13 : Issue 266

Today's Topics:
       MAJOR SOLAR FLARE ALERT - 2 EVENTS - 12/13 MARCH
   UPDATED POTENTIAL GEOMAGNETIC STORM WARNING - 07:30 UT, 13 MARCH
             Re: Not about space (sorry)
     MAJOR SOLAR FLARE ALERT - HIGH IMPACT EXPECTED FOR 16 MARCH

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Date:    Wed, 13 Mar 91 01:23:32 MST
From: [e-mail] (CARY OLER)
Subject: MAJOR SOLAR FLARE ALERT - 2 EVENTS - 12/13 MARCH
X-St-Vmsmail-To: st%"[e-mail]"

                        --  MAJOR SOLAR FLARE ALERT  --

                                MARCH 13, 1991

                              Flare Event Summary
                           Potential Impact Forecast


                                    --------


MAJOR ENERGETIC EVENT SUMMARY

     Two major solar flares have occurred over the past 6 to 24 hours.  The
first major event began at 12:40 UT on 12 March, peaked at 12:46 UT and
ended shortly thereafter at 12:58 UT on 12 March.  This major flare
attained a class X1.7/2B rating and was associated with a strong Type II
sweep and strong radio emissions at 245 MHz and 10 cm.  This flare was
associated with a 2,000 s.f.u. (solar flux unit) Tenflare which lasted 11
minutes.  A 55,000 s.f.u. burst was also observed at 245 MHz.  This event
is believed responsible for producing a small SID/SWF.  This major flare
originated from Region 6545 at a location of S07E59.  The event lasted a
relatively short 18 minutes.

     Another major high-level M-class flare began at 02:53 UT on 13 March,
peaked at 03:05 UT and ended at 03:11 UT on 13 March.  This event reached a
class M9.0/2B rating and was associated with a moderate intensity Type II
sweep.  It is not yet certain what region this flare originated from.
There is some dispute whether this event originated from Region 6545 or
6538.  There have been conflicting reports.  Some communications problems
have also contributed to the uncertainty.

     Region 6545 (now located at S09E51 at 00:00 UT on 13 March) is
optically and magnetically complex.  It possesses a potent Beta-Gamma-Delta
magnetic configuration and encompasses 23 visible spots in an optical DKI
configuration.  This region was responsible for the X-class flare mentioned
above and is capable of producing high-level major M-class flares and/or a
major isolated X-class flare.

     Region 6538 (which produced very energetic flaring earlier last week)
is also optically and magnetically complex and appears quite formidable in
white light as well as in H-alpha light.  This region also contains a
magnetic Beta-Gamma-Delta configuration, but has been unusually dormant in
flare-activity lately.  This is expected to change at any time, however.
Frequent M-class flaring and possible high-level major M-class and/or
isolated X-class flares are also possible from this region.  A significant
major solar flare from Region 6538 could produce high terrestrial impacts
as well as potentially strong proton and PCA activity.

     A weak proton enhancement was observed near 17:00 UT on 12 March with
protons greater than 10 MeV.  The peak flux attained was about 2 p.f.u..


POTENTIAL TERRESTRIAL IMPACT FORECAST

     Todays first major flare at 12:46 UT on 12 March will not have a
terrestrial impact.  It is uncertain whether the latter major event will
have a terrestrial impact.  The location of this flare is vital in
determining the potential impacts, and the location of this flare is still
uncertain.  If the flare originated from Region 6545, no terrestrial
impacts will likely be observed.  If the flare originated in Region 6538,
which has just now crossed into the western hemisphere, a weak terrestrial
impact may be possible on 15 March.  More significant major flaring from
Region 6538 will be required before potentially strong terrestrial impacts
might occur.

     The Potential Major Flare Warning remains in effect throughout this
week (and possibly longer).  Regions 6538 and 6545 are capable of producing
major solar flares.  Region 6538 is capable of producing proton activity
with major energetic solar flares.  Polar latitudes and satellite
operators/users should be on the alert for possible proton and PCA activity.
Polar radio blackouts are likely if a major proton flare erupts from Region
6538.  PCA activity could keep polar radio blackout conditions constant for
many hours (or possibly a few days if the event is intense).

     Further updates and/or alerts will be posted as needed over the coming
week.


**  End of Alert  **

------------------------------

Date:    Wed, 13 Mar 91 00:45:00 MST
From: [e-mail] (CARY OLER)
Subject: UPDATED POTENTIAL GEOMAGNETIC STORM WARNING - 07:30 UT, 13 MARCH
X-St-Vmsmail-To: st%"[e-mail]"

                /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                        SOLAR TERRESTRIAL BULLETIN

                              13 March, 1991

                    Updated Geomagnetic Storm Warning

                /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\


UPDATED GEOMAGNETIC STORM WARNING INFORMATION

     At approximately 22:00 UT on 12 March, a sudden magnetic impulse was
detected at many magnetic observatories.  Approximately 2.5 hours later,
the geomagnetic field became disrupted.  A major positive magnetic
excursion was measured over most middle and high latitude observatories
accompanied by moderate to strong disruptions on the HF bands.  Only a
single magnetic perturbation occurred, and has been followed by generally
unsettled to active conditions over the middle latitudes.  High latitudes
have experienced minor storming.  Our local magnetometer was down for
routine maintenance at the time of the major magnetic excursion, but was
brought on-line during the declining phase of the perturbation.  The
magnetic excursion (at our site) exceeded 300 gammas and occurred over a
time span of about 10 to 15 minutes (the declining phase).  Other sites
have reported larger excursions.

     The geomagnetic field is not expected to reach storm level thresholds.
Generally active conditions can be expected.  Northern middle latitudes can
expect periods of minor magnetic storming.  High latitudes can also expect
to experience minor storm level perturbations.  Central and southern middle
latitudes can expect unsettled to active magnetic conditions over the UT
day of 13 March.

     The major magnetic excursion was a surprise.  An increase in activity
was expected to follow the magnetic SI, but was not expected to be nearly
as energetic as it was over the middle latitudes.  Conditions at the
present time are relatively stable.  Activity has increased somewhat, but
is not near storm levels except near the auroral zone where minor storming
is in progress.

     Auroral activity has increased significantly over the past several
hours.  Northern middle and high latitudes are witnessing moderate to high
auroral activity.  Some southward migration of the auroral zone has
occurred, but no significant southward migration is expected.  No low
latitude auroral activity will be visible.  However, if major flaring
continues, auroral activity could appear in the lower latitudes later this
week (see the solar flare alerts).

     The Potential Geomagnetic Storm Warning remains in effect at least
until 24:00 UT on 13 March.  An update will be posted early on 14 March or
may be combined with a major solar flare alert if major flaring continues.


**  End of Bulletin  **

------------------------------

Date: 10 Mar 91 21:20:26 GMT
From: unisoft!hoptoad![e-mail]  (Tim Maroney)
Subject: Re: Not about space (sorry)

In article <[e-mail]> [e-mail] (John Hyde)
writes:
>I'm writing a term paper for a class, the title of which will be
>something like "Email and Electronic Bulletin Boards:  Present and
>Future Effects on Society."  I would like to make the case that these
>two media have the potential to have as much effect on the world as
>the printing press did.
>
>The movie Star Trek VI was originally going to be done with young
>actors playing the roles of the familiar characters, set at Starfleet
>Academy.  Word spread instantly through the net, a letter writing
>campaign was initiated, and the idea was scrapped.

Awesome.  Move over, Amnesty International.
--
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, [e-mail]

"This signature is not to be quoted." -- Erland Sommarskog

------------------------------

Date:    Wed, 13 Mar 91 14:26:24 MST
From: [e-mail] (CARY OLER)
Subject: MAJOR SOLAR FLARE ALERT - HIGH IMPACT EXPECTED FOR 16 MARCH
X-St-Vmsmail-To: st%"[e-mail]"

                        --  MAJOR SOLAR FLARE ALERT  --

                                MARCH 13, 1991
                                   Alert #2

                              Flare Event Summary
               ** POTENTIALLY HIGH TERRESTRIAL IMPACTS EXPECTED **


                                    --------



MAJOR ENERGETIC EVENT SUMMARY

     Two additional major solar flares have occurred over the past 24 hours.
The first major event was rated a class X1.3/2B and seems to have been
associated with a Type IV sweep.  Several Type IV sweeps have been observed
recently.  The event began at 08:00 UT, peaked at 08:08 UT and ended at 08:13
UT.  The flare was located within Region 6545 near S10E45 (unofficial).  The
flare was associated with a strong 1300 s.f.u. Tenflare at 08:02 UT.

     The second major flare erupted at 15:42 UT, peaked at 15:48 UT and
ended at 16:02 UT.  This event was rated a class X3.9/1N.  A strong
Tenflare of 3600 s.f.u. was also observed with this flare.

     Satellite protons increased to near event thresholds recently.  The
peak proton count reached 9 p.f.u. (10 is the event level).  It has since
declined and is presently holding at near 4 p.f.u..

     Region 6545 is a potent region containing large sunspots in close
proximity to one another.  Magnetic fields are high and gradients are
strong.  This region will continue to produce major solar flares of class X
or M intensities.  Protons could easily surpass event thresholds if flaring
continues.

     Region 6538 continues to remain fairly dormant in flare output, but
contains all of the ingredients necessary to begin major flaring again.  It
is expected to begin to produce at least M-class flares anytime now.


POTENTIAL TERRESTRIAL IMPACT FORECAST

     A POTENTIALLY HIGH TERRESTRIAL IMPACT IS BEING FORECASTED FOR 15, 16
AND POSSIBLY 17 MARCH!

     A MAJOR GEOMAGNETIC AND AURORAL STORM is possible on 15 and/or 16 March.
Data obtained from Pioneer Venus show that the solar wind velocity has
increased dramatically to values near 970 km/s with a strongly directed
southward magnetic component.  It is possible that the earth could be hit
with some of the material streaming by this satellite.  Current predictions
estimate that the geomagnetic storming could push the A-index to levels
near 50 on 16 March.  Middle latitude magnetic K-indices are expected to
be sustained near 5 and 6 with possible brief periods near 7 (if activity
is more intense than expected).  High latitude magnetic activity could
surpass A-indices of 100 with associated K-index values between 7 and 9 (it
should be noted that a K-index of 9 is the top of the scale).  Magnetic
perturbations over high latitudes could approach 1,500 to 2,000 gammas.
Middle latitudes could see fluctuations between 100 and 250 gammas (for
mid to southerly middle latitudes).  Northerly middle latitudes could see
fluctuations ranging from 200 to 1000 gammas.

     A MAJOR geomagnetic storm is possible.  Storming is expected to peak
on 16 March.  A sudden storm commencement associated with the arrival of
the interplanetary shockwave is expected sometime on 15 March.  It is
difficult to determine when this shock might hit, but preliminary estimates
suggest that the shock could arrive near 12:00 UT on 15 March.  Minor to major
geomagnetic storming could follow shortly thereafter.

     A POTENTIAL LOW LATITUDE AURORAL ACTIVITY WARNING is being issued for
16 March.  Auroral activity could become visible at southerly middle and some
low latitude regions if storming reaches or exceeds predicted levels.  High
latitude and northerly middle latitudes could experience auroral storming
with possible high auroral activity.

     Significant VHF auroral backscatter will be possible late on 15
and on 16 March.  HF conditions are expected to be quite disturbed on 16
March.  Significant fading, flutter, noise and absorption are possible.  If
storming occurs, MUF's will decrease and LUF's will increase notably.
Updates and/or modifications to this forecast will be posted when available.

     Major flaring is expected to continue.  Proton and/or PCA activity
could occur anytime.  Watch for possible future warnings and/or alerts.

**  End of Alert  **

------------------------------

End of SPACE Digest V13 #266
*******************