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Location: UFOUpDatesList.Com > 1997 > Nov > Nov 15

Mexico City - More Video Analysis

From: bruce maccabee <brumac@compuserve.com>
Date: Sat, 15 Nov 1997 00:48:53 -0500
Fwd Date: Sat, 15 Nov 1997 09:58:14 -0500
Subject: Mexico City - More Video Analysis


I have discovered new and significant information from my
continued study of the video.   Before I present it I would
like to point out that I am working from a video copy made from
a tape that was received over the "airwaves" by a person in
Mexico City.  Therefore it is not as clear as the original. In
fact, the pictures in the just-published November issue of the
MUFON Journal are clearer.  Hence I many hope for yet further
information when I get a "perfect" copy of the video.

Those of you who subscribe to the MUFON Journal will see
printed therein information that was circulated in the network
over a month ago (Bill Hamilton's initial report of Oct 1 on UFO
Updates and a report from UFO Roundup of Oct. 12).

Further analysis of the video shows that the zoom factor is about
4.  This is low for the typical videocamera. Probably the camera
was partly zoomed before the first video images. I assume it was
zoomed to maximum. This has bearing on the focal length and on
the field of view and on the hoax hypotheses discussed in the
first part of this analysis.

The UFO appears on video for 23 seconds.  The video continues for
another 11 seconds after it disappears behind the second
building. At the beginning of the video the UFO is stationary for
about 8 seconds before moving to the right.

Further checks of the wobble rate confirm that the wobble cycle is
approximately 2.2 (+/- 0.2) sec/wobble, or about  (1/2) wobble per
second.   A further check of the rotation rate confirms the roughly
0.16 cycles/sec. or about 6 sec per revolution cited previously.

Bill Hamilton wrote that the rotation rate was once per second,
but I don't think this is correct. The moving dark spots are what
give the impression of rotation.

I measured the number of frames it takes for a spot to move 0.2
times the length (diameter) of the (assumed circular) disc

This motion was measured at the center of the disc image and so
corresponds to an angle (relative to the center of the disc) of
0.2 radians (almost exactly).  This measurement was difficult to
make because the dark spots were so diffuse (could do better with
a better copy of the video blowup).  However, I found that it
requires 5 to 7 frames for a spot to move 0.2 rad.  Picking 6
frames as an average number, this means 0.2 rad per (6/30 sec) or
 0.2 rad / (1/5 sec)  = 1.0 rad/sec.   But there are 2 pi = 6.28
(approximately) radians in a revolution, so it requires 6.28
second per revolution.  The inverse of this is 0.16 revolutions
per second, which is the value given in the first part of this
analysis (but without justification).

The UFO's horizontal motion relative to the left hand edge of the
first building was discussed in the first part of this analysis.
The velocity was found to be constant to a good degree of
accuracy as long as the UFO was visible.  After the UFO
reappeared above the first building and traveled in a level
trajectory toward the second it slowed down.  Just before it
disappeared it was going about 0.6 times as fast as the initial
horizontal speed.  The measurements suggest some slight
oscillation in the speed, but higher resolution will be necessary
to prove this.

Careful measurements of the image size using the negative image
format (sky dark) and adjusting the brightness so that the UFO is
just "above" visible, I find that the initial length on this 1.6x
blowup is 38 mm. While above the center of the first building
it's length is about 40 mm, suggesting that it got closer.  Then,
just before disappearing its length is 33 mm long indicating that
it moved away.

A study of the image brightness has revealed significant
information which is consistent with the above image size
measurements.  By setting brightness levels appropriately I
determined that the image brightness is lowest (greatest contrast
against the bright sky) when the UFO is over the first building.
The image brightness is slightly higher (slightly less contrast)
before the UFO moves behind the first building.  Then, of
particular significance, is the fact that as it moves toward the
second building the contrast decreases (image brightens)
continually until it disappears.

The significance of the image brightness changing (image contrast
changing) is based on the haze effect or atmospheric
"extinction." The farther an object moves away into a bright sky
background with haze, the brighter it appears, eventually at some
distance reaching the brightness of the sky background, at which
distance it "disappears" because there is no longer any contrast
between it and the background.  For example, a black sphere that
moves away from the observer will grow smaller but it will also
increase in brightness.  The increase in brightness is a result
of light scattered by haze particles or dust or air molecules
into the path of the light from the sphere to the observer. In
this case we have an object, the UFO, which is not as bright as
the sky background.   When first seen it has some brightness
level and contrast to the sky  and a size measurement of about 38
mm.  Then a few seconds later it's brightness is lower (and
contrast is greater) and the image size is greater, both of which
are consistent with the UFO moving closer to the camera (about 5%
closer).  Then as it moves to the right the brightness increases
as the size  decreases (by about 18%) indicating the object
started moving away  from the camera before  it disappeared
behind the building.   In fact, it  appears to have initiated a
curved path away from the camera just  before it disappeared
behind the building.  One may imagine that, if  this not a VERY
clever hoax, the UFO never appeared on the right side of the
second building because it had made a "left turn" (but not at
East Gate) and disappeared in the distance.


The only conclusion possible so far is that if this is a
hoax...... then we should all turn left and disappear into the
haze..... (where is that East Gate when we need it?)

Search for other documents from or mentioning: brumac

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