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Location: UFOUpDatesList.Com > 2007 > Jul > Jul 18

Re: The 1952 Tremonton Utah

From: Bruce Maccabee <brumac.nul>
Date: Tue, 17 Jul 2007 18:35:59 -0400
Archived: Wed, 18 Jul 2007 10:54:59 -0400
Subject: Re: The 1952 Tremonton Utah


>From: Martin Shough <parcellular.nul>
>To: <ufoupdates.nul>
>Date: Tue, 17 Jul 2007 14:02:58 +0100
>Subject: Re: The 1952 Tremonton Utah 'Seagulls'Confirmation?

>>From: Michael Tarbell <mtarbell.nul>
>>To: ufoupdates.nul
>>Date: Sun, 15 Jul 2007 10:01:53 -0600
>>Subject: Re: The 1952 Tremonton Utah 'Seagulls' Confirmation?

<snip>

>>It is notable that the objects
>>apparent diameters diminish smoothly by ~30% during the film,
>>indicating that they are traveling _away_ from the camera, such
>>that the raw angular rate data would underestimate the actual
>>speed at range.

>This is an interesting point, Mike. I recall seeing this 30%
>somewhere. Do you have the reference?

>Hartmann's meta-analysis of the Baker and Navy studies assumes
>that because the objects were filmed at high elevation there is
>no significant component of velocity in the line of sight, but
>evidently a 30% monotonic diminution of angular size suggests
>about a 1.4 range ratio between first and last frame. If the
>group of "birds" was 2000 ft away at its nearest then it was
>about 2800 ft away by the end. During 75 seconds this equates to
>a little over 7 mph. Transverse angular rates measured within
>the group correspond to about 9 mph at 2000 ft, representing
>minima for internal velocity within the group, so that the lower
>bound on the total velocity for any group member is the vector
>sum of a bulk radial rate of ~ 7 mph and 9 mph = about 11.5
>mph.

<snip>

>Another point that concerns me about the overall diminution of
>angular size is Hartmann's suggestion (citing Al Chop and an AF
>report) that the objects are unresolved and flared due to
>overexposure. If so then the image size becomes to some unknown
>extent a function of brightness as well as distance, and in fact
>one of the official documents (NPIC analysis I think) pointed
>out that changes in object brightness correlated with change in
>size. Notice that about a third of the way into the film
>Newhouse stopped down from f/8 to f/16 (because he feared he
>might be overexposing). This could in itself reduce the image
>size. So I'd like to know that the 30 % size reduction is indeed
>"smooth" and is a figure arrived at after subtracting the
>reduction in flare.

I would like to add something to this rather erudite discussion
of the Newhouse film.

I discovered, or more accurately, rediscovered the image size
vs brightness relationship while I was analyzing the New Zealand
(Dec. 31, 1978) film oh, so long ago!
I carried out experiments which showed the following:

Let "geosize" be the geometric sized image which depends
upon the focal length, F, the distance to the object, D and the object
size (transverse to the line of sight), O. Then

geosize = F (O/D)

This is simply the equivalence of two ratios: geosize/F = O/D.

However, this has to be modified when brightness becomes very
large. Light travels sideways in the film thereby increasing
the size of the image beyond its geosize according to the
relation, where I = image size including brightness effects,

I = geosize + K log (Exposure)

K is a function of the film and its development. Exposure is the
amount of light energy hitting the film (the illuminance on the
film multiplied by the shutter time, or the irradiance in W/cm^2
times the shutter time). Exposure depends upon how much light
falls on the film while the shutter is open and this also
depends upon the area of the the lens aperture which is
proportional to the square of the f#. If one had film identical
to what Newhouse used, and if it were developed in the same way,
it would be possible to determine from the test film what the
constant K is. (I did this years ago for the New Zealand color
movie film by photographing back-illuminated apertures of
various sizes using various exposure settings.) Since he changed
the f# it might be possible to deduce or approximate K from the
film itself if one had the original (sorry about that!) or a
good copy. It would be necessary to measure the sizes of the
images before and after the f stop change. IF there was very
little change then probably there was little image growth due to
exposure. If there was a large change (e.g., 30%) then the image
sizes at f/16 would probably still be "inflated" somewhat by
brightness.


But, aside from the interesting but tedious technical analysis,
I always believed that they were not seagulls because I couldn't
imagine Newhouse (after his wife attracted his attention to the
objects) would be so confused by birds flying overhead that he
would stop the car to take their picture. If the objects were of
sufficiently large angular size for him to deduce shape and if
they and been birds he'd have known it. As I recall, Ruppelt
pointed out that when Newhouse was first interviewed the
discussion was centered on the film and no one asked for a
detailed description of what the objects looked like at the time
he first saw them. And at the Robertson panel discussion all
they talked about was the film. Nothing about their initial
appearance. (Same with the Marianna/Great Falls Montana film.)



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