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Comments on Mexico City Video of 08-06-97 - 1/2

From: bruce maccabee <brumac@compuserve.com>
Date: Thu, 13 Nov 1997 21:44:29 -0500
Fwd Date: Fri, 14 Nov 1997 10:23:03 -0500
Subject: Comments on Mexico City Video of 08-06-97 - 1/2



INITIAL COMMENTS ON MEXICO CITY VIDEO OF Aug. 6, 1997

PRELIMINARY DISCUSSION ----***TO BE REVISED AS NECESSARY***


THIS IS BASED ON ANALYSIS OF A VIDEO COPY (originating source unknown)

The copy includes the direct video, a 1.6x blowup negative video
(sky is dark, UFO appears bright against sky) and a 7x blowup.

The video begins with a "wide angle" shot and immediately zooms
in. Once zoomed in it stays that way. The wide angle shot shows
numerous nearby buildings. They appear dark against the sky
background. What seem to be distant structures are faint in the
haze, i.e., they have low contrast with the sky, as expected from
atmospheric extinction.  The atmospheric extinction coefficient
could be estimated from assumed intrinsic brightness of the
buildings if the distances were known. This coefficient is
probably given in meteorological reports for the time (the
"visibility" or "visibility distance"). This could be important
in determining the intrinsic brightness of the UFO, assuming it
is a real object at some distance. I do not know the distances of
buildings in the pictures but something like thousands of feet to
a mile or so seems more reasonable than, say, 3 to five miles.
There are enough structures in the background so that using
parallax one should be able to locate ths position of the
videographer.

The UFO is generally well centered. The camera jiggle is obvious
and looks as one would expect for a hand held camera. The jiggle
is much more noticeable after zoom. Once the UFO starts to move
to the right the camera pans with it, jiggling as it goes. The
UFO motion seems to be at about a constant rate and so is the pan
motion. After the UFO disappears behind the second building the
camera sighting direction continues to move to the right as if
the videographer expects to see the UFO appear from behind the
second building, which would be logical based on the previous
continuous motion.

The UFO is initially stationary but obviously tilting back and
forth or wobbling at a constantrate. A 7x video blowup shows
left-to-right motion of diffuse (edges not sharp) darker areas or
dark spots which seem to be on the rim of the UFO. If these are
fixed to the surface, then they suggest, but do not prove,
rotational motion, counter-clockwise as seen from above. (The
dark spots could be "moving" left to right on a non-rotating UFO,
thereby giving the impression of motion  just as changing light
patterns in an electronic sign can give the impression of
motion.) I would have to say that the way these appear at the
left edge of the UFO and then move to the right is not exactly
what I would expect if the spots were fixed with respect to the
surface of the UFO.   However, the "funny appearance" of the dark
spots as they appear and move may be a result of the atmospheric
haze (causing low contrast) plus the artifacts of electronic 7x
zoom (these features would be very small, almost invisible, in
the un-electronic zoomed images).  there more be more clarity in
the original video.  Aside from the "funny appearance," the
combination of the motion of the dark spots and the wobble
certainly gives a good impression of rotation with wobble or
"precession" (see below).   An estimate of the rate of the
assumed rotation, as based on the motion of the black spots, is 6
to 7 seconds per revolution (about 0.16 rev/sec or 1.0 rad/sec).
In other words, it is not spinning rapidly.  The wobble requires
about 2 sec to complete a cycle (0.5 rev/sec or 3 rad/sec).

After remaining stationary for several seconds the  UFO then
"instantaneously" accelerates (see below) to a constant velocity
which takes it to the right on an upward sloping path. It seems
to pass behind the upper left corner of one building and then,
because of its upward trajectory it appears above the building.
Frame by frame analysis of both the disappearance and the
reappearance show consistent "cutting away" of the image, as if
it were a real object moving slowly out of view behind the
building and then reappearing from behind the building. After
reappearance it continues its steady right hand upward motion and
wobble. If moves toward a second, higher building. It disappears
for good behind the second building.

After the initial camera zoom the UFO image on a 14" diag monitor
is about 25 mm wide and about 7 mm high. Since I don't know the
effective focal length of the camera lens I can only hazard a
guess that the angular size might be on the order of 1/2 to 1
degree.   Just before it disappears the second and final time the
UFO image length is 20 mm.   This suggests that it was about 25%
farther from the camera when it went out of sight.

The first nearby building that the UFO goes "behind" - or appears
to go behind - has some square windows 5 mm on a side on the
monitor. Hence the UFO initially appears to be about 5 times
larger than these windows. If, for example, the window were 5 ft
wide, then the UFO was more than 25 ft in diameter (assumed
round, but there is no proof of this - no "top view" or "bottom
view"). assuming it was as it appears, farther away than the
building. All further dimensions are scaled according to this
assumption, lacking any further information. The UFO was
apparently farther away than the building, perhaps as much as
twice as far, but not very much farther because it would have
been barely visible in the the smog/haze.  The UFO image has
areas that are darker than the sky background, an important
factor discussed below. If the UFO were miles away it would "fade
into" the haze and the dark areas would not be as obvious as they
are.

If the UFO were twice as far as the building, then it would be
about 50 ft in diameter, assuming as before that the square
windows are 5 ft wide.

I have studied the UFO acceleration by plotting the position of
the right end of the UFO image relative to the building it (seems
to ) disappear behind.   For several seconds the spacing is
constant with fluctuations (83-85 mm on the monitor).
Fluctuations in the spacing are a result of the continual wobble
of the UFO combined with the frame-by-frame fluctuations in the
image shape and "edge fuzziness", a phenomenon caused most likely
by electronic noise in the video camera. Then, suddenly, there is
motion to the right (toward the building). The abrupt change from
stationary to moving is noticeable to the naked eye when running
the video forward (in time).   The UFO image is seen to suddenly
start moving to the right, what seems to be an "inertia-less"
(instantaneous) onset of motion, with what appears to be a
constant velocity.

When viewed in reverse, the UFO is moving constantly to the left
and appears to suddenly stop, as if hitting an invisible brick
wall.  (Crash dummies inside?)

The left edge of the building is sufficiently sharply focused in
the 1.6X blowup video negative (sky dark) to allow reasonably
accurate (to within 1 mm on the monitor) measurements of the
spacing between the left end of the UFO image and the image of
the edge of the building. This method allows for measurement of
the UFO motion irrespective of the camera jiggle, i.e., by using
the building as a reference the camera jiggle is essentially
removed. (It still has the effect of smearing the edges of the
images slightly.) A graph of spacing vs frame number shows the
following odd result: in one (or less than 1) or at most 2 frames
the UFO achieves its full foward speed. There appears to be no
swinging as one would expect for a model hanging on a string.
Also, the rotation and wobble (precession) do not appear to be
affected by the onset of motion.  (More precise analysis using
the original video may turn up some slight changes in the
rotation and wobble.) Using the estimate of the UFO being 25 ft
in diameter, the steady speed to the right corresponds to about
16.9 ft/sec or about 11.5 mph. This would be doubled if the UFO
were twice as far away (and changed in proportion to the assumed
UFO size and distance scale). If it achieved this 16.9 ft/sec
speed in 1 frame, 1/30 sec, then it achieved an acceleration of
about 16 "g's" (16 times the 32 ft/sec^2 acceleration of
gravity). If in two frames, then 8 g's. This sort of acceleration
would be enough to cause wobble in any model hanging on a string.
 This acceleration, since it seems to cause no effect to the
"normal" wobble and rotation of the UFO must be acting through
its "center of mass" (else, there would a torque or twisting
motion that would change the wobble in some way). If the UFO
weighed 1 pound and accelerated in 1/30 sec, then the force
applied would be 16 pounds. If it weighed 1 ton (2,000 lbs) the
accelerating force would be the equivalent of the weight of 16
tons.

NOTE: THESE SPECIFIC NUMBERS ARE ONLY ROUGH ESTIMATES TO GET "IN
THE BALLPARK".  THE ACTUAL VALUES DEPEND UPON DIMENSIONS WHICH
ARE PRESENTLY ONLY GUESSED AT.

CONSIDERING THE HOAX HYPOTHESIS:

In general there are three possibilities: a hoax, a
misidentification or the "real thing" (a True UFO - unexplainable
as conventional a phenomenon). The possibility of a
misidentification seems unlikely because of the shape. Even if
one could prove that there was a 25 - 50 foot blimp with a
gondola on top that was hovering and rocking so that the front
and rear ends alternately went up and down (but not rotating) and
having dark areas moving long the side near toward the camera,
this would not explain the "instantaneous" acceleration. That
leaves only the hoax or the real thing.

Factors to be considered and their relevance to the hoax
hypothesis are: 1. The presumed hoax must either use a model of
some sort or it is an electronic construction

1a. If a model, then it is not likely a full sized model at a
great distance (thousands of feet, beyond the buildings) from the
camera (rotating, wobbling, accelerating), but more likely a
small model within a room where the video was shot.  Therefore
reject the full sized model hypothesis.  (However, it is to be
noted that this is the only method that could potentially create
witnesses to the "UFO" who were not associated with the hoax.)

Search for other documents from or mentioning: brumac

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