(meteorobs) OT -Proceeding with IR block fireball detonationsystem.
stange34 at sbcglobal.net
Sat Nov 29 01:41:40 EST 2008
What I am attempting Chris is to determine the internal manner & shape of a
I believe a fireball that fractures (from previously formed weaknesses)
before an explosion will be different in the coherent (visible) light shape
than a fireball that explodes due to the difference in frontal & rear
pressure, and both of these would be different from one that is terminally
consumed as a bright flash. And anything else I do not know about in the way
fireballs explode. Like how it (really) fragments or spreads fragments at
the time of the peak explosion IR emission which obliterates photography.
All explosions as you mention start as a point source, but is there a shape
to it visible in white light that can suggest how or why it exploded? Or,
how fragments separate during an explosion?
This system would be useless for normal meteors and is not intended for
that. I hope a blown up image (might) yield unexpected detail and results
given the crude way I am attempting to image it. It's all a guess as to what
the result will be.....and not knowing is my driving force.
----- Original Message -----
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2008/11/28 22:02
Subject: Re: (meteorobs) OT -Proceeding with IR block fireball
> I don't really understand what you're trying to accomplish. At the pixel
> scale of allsky video cameras, all meteors are point sources. You can't
> resolve anything- even a large explosion is still a point source. Where is
> information lost? The main problem is the low dynamic range of the camera.
> If you want to record the dimmest possible meteors, you'll saturate
> ones. That represents a loss of information. A good video system with a
> maximum sensitivity of mag 2 will saturate at about mag -4, or maybe
> mag -6
> for a more esoteric camera. Still, nowhere near enough to accurately
> the magnitude of a significant fireball. Of course, you can use filters to
> shift the range, but only at the expense of missing more ordinary meteors.
> (I solve this problem using a reference white target, that I can use to
> the reflected light for bright events.)
> You may also consider the effects of blooming to result in a loss of
> information. Because the shape of the meteor profile changes, it can be
> difficult to determine its centroid, and therefore the meteor position.
> Since (despite the occasional witness report to the contrary) meteors
> suddenly change direction, you can usually make an accurate determination
> position by considering the entire sequence, so I haven't considered
> blooming a serious problem.
> I really don't think you want to include any filters in your system. If
> want low sensitivity for bright fireballs only, a color camera might make
> more sense, since you can extract some interesting spectral data from the
> raw image.
> Chris L Peterson
> Cloudbait Observatory
> ----- Original Message -----
> From: "stange" <stange34 at sbcglobal.net>
> To: <meteorobs at meteorobs.org>
> Sent: Friday, November 28, 2008 10:17 PM
> Subject: (meteorobs) OT -Proceeding with IR block fireball detonation
>> Curiosity as to how a bright fireball might look inside the light blossum
>> during an explosion is my downfall....
>> The system being retro-fitted now will utilize an 18" hemispherical
>> 1/3" CCD camera with an auto-iris, fixed 8.5 mm, 1:1.3 Computar lens
>> designed for a 1/2 CCD. Initial Camera a 1/3" Sony SPT-M124 will be
>> with a PC164C. A Baader IR filter will be mounted (in) a machined adapter
>> fit inside the light shield of this lens up very close to the uv coated
>> Preliminary indoor tests using Handyavi set for 640X480 RGB24 (30 FPS
>> unfortunately), look workable with the camera about 40" above mirror
>> Fingers crossed.
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