(meteorobs) RE: Explosion Observed

Wed May 17 07:06:48 EDT 2006

Bob and Becky,

GRBs are gamma ray bursts, first discovered by the satellites send up to monitor atmospheric nuclear testing, since nuclear explosions emit gamma rays. The GRB event must be one of the most powerful events in the universe and for a few seconds a BRB can outshine an entire bunch of galaxies. There appear to be at least two types.

Check

 http://en.wikipedia.org/wiki/Gamma_ray_burst 

for more.

Terry

-----Original Message-----
From: meteorobs-bounces at meteorobs.org on behalf of Robert Anderson
Sent: Mon 5/15/2006 7:12 PM
To: 'Jan Verfl'; 'Global Meteor Observing Forum'
Subject: RE: (meteorobs) RE: Explosion Observed

All, 

Please help me here. What is a GRB? 

Sorry for the "tongue in cheek" measurements. I tried to find known
references to help describe it as best I could, but due to the rapid nature
of the event it was difficult. This is my first attempt to report an
observation and in the process struggled over the magnitude and size.

If it was a "stationary meteor", then would not another observer at
different latitude viewing the same object notice a trail?

Regards,

Bob and Becky Anderson
Tulsa, OK
-----Original Message-----
From: Jan Verfl [mailto:verfl.meteors at seznam.cz] 
Sent: Monday, May 15, 2006 5:40 PM
To: 'Global Meteor Observing Forum'
Cc: bob_becky.anderson at sbcglobal.net
Subject: RE: (meteorobs) RE: Explosion Observed

Hello all!

A GRB observed visualy would be a fantastic breakthrough, indeed! Anyway
this is definitely _not_ impossible, but the probability of such a sight is
enormously low and without any other evidence, there is no way to tell, if
it is the case.

The mythology of the "stationary meteors", the ones that fly precisely in
you direction an thus do not exhibit any apparent movement, has a long
tradition among observers here. I call it "the mythology", because such an
event was never reliably observed. Why? It's extremely difficult indeed! To
say something did not move at all, I guess you must look at it directly, so
such a "stationary meteor" has to appear luckily near the very center of
your FOV. It still has to be quite bright, because a non-moving object does
not easily attract your attention - this latter condition may nevertheless
be easy to satisfiy, as all the light from the "statioanry meteor" comes
from one point of the sky, thus can be effectively concentrated. Anyway,
this is a very naive (my) opinion and I think that some subtle
considerations including more of the true physics would have to be caried
out to see, if this really works.

What is the real problem is, when you see an event that could be a
stationary meteor, how can you tell it just was not a sunlight reflection
from a satelite solar panel? Usually meteors are distinguished from Iridium
flares and whatsoever by their speed, bud what to consider in the case of a
perfectly stationary source? How exactly can a human eye tell, If the source
was really stationary. All those question remain open to me and are of
particular intersted to me, because I have seen about 3 events in my life I
would clasify as a stationary meteor, but never well enough to tell more
about it. Probably there is a way to get an insight - the video
observations! But as I am not aware about their capabilities and time ans
spatial resolution, I cannot tell if they really do help with this. Many
people on the list do video observations - has anybody ever recorded a truly
stationary meteor?

There are still some unclear information in the original report. As I
understand it, Bob Anderson saw it with his bare eyes. How can he compare
anything to the diameter of Jupiter, as 40 arcseconds mean a perfect point
(as well as the 80 mentioned for the "explosion") for human eye? Jupiter is
a bright thing, so it appears "big" on the sky, bigger then the sky, but
this is purely an artifact on the vision. But he reported that the
"explosion" was twice as big, but fainter - this means that its apparent
size cannot originate in its brightness, so it must have had a true
resorvable angular dimension. As 80 arcseconds are still a point, it could
have been underestimated - I do not believe that any unaided observer can
say anything valuable about objects smaller then 3 arcminutes at least,
especially at magnitude of +2. Anyway, it is still possible, that the
apparent size was seen only due to the evolution of the brightness of the
object and was not real. Siplmy speaking, a variable object is more
interesting thn a star and thus tends not to look completely pointlike for
the eye. This is a very interesting topic, because a real angular shape
would of course disqualify the GRB (thiey are very distant and thus
pointlike). 

Clear skies,
Jan Verfl

> -----Original Message-----
> From: meteorobs-bounces at meteorobs.org 
> [mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Roberto G.
> Sent: Monday, May 15, 2006 11:19 PM
> To: Global Meteor Observing Forum; david at exposquare.com
> Subject: Re: (meteorobs) RE: Explosion Observed
> 
> From: <GeoZay at aol.com>
> To: <meteorobs at meteorobs.org>; <david at exposquare.com>
> Sent: Monday, May 15, 2006 9:21 PM
> Subject: Re: (meteorobs) RE: Explosion Observed
> 
> 
> > 
> >>>Can anyone explain what this non-member might have  observed?<<
> > Going just by what is said, sounds like a point meteor.
> > George Zay
> 
> If you observe a similar phaenomenon you can think too at 
> a possible GBR.
> Best greetings.
> Roberto Gorelli
> 
> ---
> Mailing list meteorobs: meteorobs at meteorobs.org
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