GAMMA BURST: Need help from hams!!! (fwd)

David V. Rogers
Wed, 30 Sep 1998 08:51:43 -0400 (EDT)

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Date: Wed, 30 Sep 1998 07:33:59 -0400
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Subject: GAMMA BURST: Need help from hams!!!

>Date: 	Tue, 29 Sep 1998 21:40:57 -0600 (MDT)
>Sender: owner-qrp-l@Lehigh.EDU
>From: Paul Harden <>
>To: "Low Power Amateur Radio Discussion" <qrp-l@Lehigh.EDU>
>Subject: GAMMA BURST: Need help from hams!!!

>There was a MAJOR GAMMA RAY BURST that occured on August 27, 1998 at
>1022 UTC from a neutron star 15,000 light years away.  This burst was
>so strong, it ionized the E and F layers on the NIGHT side of the Earth,
>ionized the D-layer for extreme absorption for many minutes, and
>saturated gamma- and X-ray sensors on satellites.  Only two other
>major gamma ray bursts have ever been detected, one in 1979 and another
>in 1984.  This is an extremely rare astronomical event that is caused
>by a generation of power so intense it is almost beyond explanation.
>Experimental physics VLF monitoring circuits maintained by Stanford
>University recorded this absorption down to the tens of KHz!!!  But
>because this event occured in the very early morning hours in the U.S.,
>there is virtually no record of this event.
>1022 UTC?  (That is 0322 Pacific Time, 0422 Mountain, 0622 Eastern U.S.
>Time)  The VLF records show about a 5 minute period of total RF
>absorption ... that is, a total communications blackout.  However, it
>is not known what duration this event may have had in the HF portion
>of the spectrum, whether shorter or longer (the later is likely).
>This would have caused a total/near total blackout on the AM broadcast
>band (550-1750 KHz), 40M, etc. for several minutes.
>If you have a recollection of noticing this event, or specific data
>from say a QSO in progress, please send me the information and/or
>post it to either QRP-L or G-QRPL.  This is an opportunity for hams to
>make a contribution to a rare scientific study if you were lucky enough
>to witness it in some form or another.
>There was also a SEVERE geomagnetic storm that occured shortly after
>this gamma ray burst on August 27th ... which is being investigated if
>it may have been triggered by this event.
>>From the Stanford University VLF data, it appears the blackout would
>have occured from a line drawn from just west of Hudson Bay in
>Canada to the tip of Baja California and WESTWARD to central Russia.
>This was the side of the Earth that was facing the neutron star when
>the gamma rays arrived.
>This is an extremely rare and interesting astronomical event, and I
>will post some details on what happened, what the significance of
>gamma radiation from 15,000 light years away is, etc. in the next day
>or two.
>About an hour ago, a press release with the VLA images of the neutron
>star (SGR 1900+14) was placed on the observatory's web page at:
>    for those so interested in the images.
>I think the complete path is
>Identifying the source of this gamma ray burst was observed, in part,
>by our own Dr. Dale Frail, using the Very Large Array Radiotelescope
>in Socorro, New Mexico.
>Thanks for your help.
>72, Paul NA5N
>National Radio Astronomy Observatory
>Socorro, New Mexico

Date: 	Tue, 29 Sep 1998 23:18:23 -0600 (MDT)

From: Paul Harden <>
To: "Low Power Amateur Radio Discussion" <qrp-l@Lehigh.EDU>
Subject: Re: GAMMA BURST: Need help from hams!!!

On Tue, 29 Sep 1998, Brian Mileshosky wrote:
> I was just wondering why all the
> hype of this event just came out now?  According to your report to the
> list, this event happened in August...why so long to report it? 

Brian (and others),

Actually, that is a very good question that has an interesting answer,
at least as I understand it from all the activity at the observatory
past couple of days.

First, the VLA radiotelescope is used by visiting astronomers 24 hours
a day and is "booked up" about 6 months in advance.  To use the
instrument, you must submit an observing proposal, which are reviewed
and those with proper merit are granted for the next 6 month period.
There is virtually no free time on the radiotelescopes.

The gamma burst occured on August 27th, and it was not until Sept. 3rd
that Dr. Frail was able to "steal" some telescope time on the VLA to
search the region of the sky where it appeared to originate from.
Fortunately, he was able to find an object, SGR 1900+14, that was
still emitting vast amounts of power.  A mere few days later, the
star returned to being a low-level "point source" object.  While this
pretty much confirms the source of the gamma emitter, now referred to
as a "magnetar," it *is* a sample of one, and with such a short duration
event, it was not observed by anyother instruments other than the
satellite detectors (which saturated from the power and thus provides
little real data).

Astronomers are brilliant people, but like any science, you tend to
be confined to your own discipline.  There was no thought of checking
other indicators, such as if our ionosphere reacted to it, because
prior to yesterday, astronomers would tell you that a gamma burst to
do that would just have to be huge beyond human comprehension.  And
with the satellite sensors saturating, nobody knew how powerful this
event really was, but certainly not powerful enough to ionize our

Then yesterday, it was learned that Stanford University recorded a
total absorption event on their VLF path receivers around 10 KHz.
This is a system of transmitter and receivers located at various
places (like Bangor, WA and CA with receivers in Boulder, CO to
mention a few I know of) that use VLF to perform plasma physics
experiments.  Their August 27th data shows total absorption occuring
at 10 KHz (not sure of the exact frequency used) at exactly 1022 UTC
and lasting 5 minutes.  This is an unexplained phenomenon at such low
frequencies, as it would require a huge ionizing event where the
radiation reached the lower portion of our atmosphere, if not striking
the earths surface itself.  In turn, they contacted the solar people
to find out if a major flare had occured at that time, even though
the effected area was in darkness.  Eventually this led to realizing
it occured exactly when the gamma burst arrived, and suddenly
scientists of various disciplines started talking to eachother.

The "big deal" about this is that for gamma radiation to strike the
earth, coming from 15,000 light years away, sufficient to ionize
even the D-layer (closest to the earths surface) and cause absorption
into the KHz range, would require power unlike ever before recorded.
Another big deal is that gamma radiation, itself, would likely not
cause a geomagnetic disturbance, if indeed the geomagnetic storm that
same day is related.  This implies that a cloud of PARTICLES (heavy
stuff) was traveling along with the radiation shock wave at nearly
the speed of light ... indeed, in itself a most unusual occurance.

In summary ... this is the FIRST TIME EVER that a celestial event outside
of our solar system has effected the earth's environment.  And that
is a "big deal."  Scientists involved mull over this data and tend to
be very cautious before making a press release with such a profound
significance, and hence the one month delay.  This gamma burst
discovery *will* alter our understanding of cellestial physics.

72, Paul NA5N