Manta Ray Visits Millbrook, NY

Other Manta Ray sightings

On 20 August 2003 Billy McNamara and Bruce Cornet witnessed the Manta Ray making a run at them from a hovering position about half a mile away due north.  It turned around about 500 feet from them, and then departed back to the north.

Duration of Performance: 5 minutes.  9:37:26 pm to 9:42:48 pm EST.
Estimated Altitude: 500 feet.
Estimated Average Speed: 10-15 mph (ranged from 0 mph to 30 mph).
Shape: Diamond, with a broad vertically flat leading edge forming a chevron shape, and a long tapering tail.
Estimated Maximum Width: About 60 feet.
Estimated Length: About 100 feet, variable.
Total Number of Lights: Varied from 2 to 5.
Number of Headlights: 2, one each at outboard angles of craft.
Number of Strobes: Varied from 0 to 2, one at nose and one at tail.

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The first frame (9:37:22 pm) is a wide angle shot.  House lights at left give perspective on distance and altitude of the Manta Ray hovering.  The observers were about 250 feet from the house and a row of mature trees to the right of the house.

Looking north:
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Looking east:
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After we first spotted its head lights to the north about half a mile away, it brightened them considerably, then slowly began to accelerate towards us.  We heard no sound until it was almost over us.  As it began to move, it dimmed its headlights back to "normal."  A small red light located at its nose flashed regularly and irregularly.  As it approached our position on a horse pasture and side of a small hill, it made a sharp turn sideways, but continued to move towards us sideways. 

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It extended the top light on its chevron-shaped nose as it continued to turn around. 

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When it momentarily came to a complete stop, it was pointing away from us and not more than five hundred feet from us.  I compare the maneuver to an ice skater making a sharp turn on ice.  It banked only slightly as it turned.  Then the diamond-shape craft began to accelerate away from us.  A light on top of the craft at its nose moved downwards as it was extended forward, and ended up on the bottom of the craft as the craft departed!  As it left, its tail light began to flash, whereas before it did not strobe.  In addition, its strobes did not illuminate any of its fuselage, something that does happen with conventional aircraft.  Its skin was stealth black.  It produced a whole range of different whining sounds like a series of electrical generators powering up.  Its estimated average speed was between 10-15 mph.  Dr. Ellen Crystall and I have independently videotaped and photographed this craft dozens of times.  Each time it did something a little different, giving us more information about this enigmatic craft.  The Hudson Valley sightings continue.

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Path the Manta Ray took.  Illustration generated by tracking the movement of the lights from video frames. The outline of the craft is shown, along with the lower nose light strobing.  Tail light could not be seen until craft began to turn.  The upper nose light came on as the craft began a shallow bank.  The movement of the nose lights highlights the extension of the nose of the craft, and their movement onto the belly of the craft, so that both could be seen as the Manta Ray departed.

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Time indicated on the left of graph; relative distance between headlights along the bottom (in mm on computer screen).

The charted movement of the Manta Ray is based on the relative distance between its two headlights.  Measurements were made on video frames used to create the animation above.  If the distance between the lights did not change with time, the craft was stationary.  The green area represents a change in orientation.  As the craft turned sideways, the relative distance between the headlights abruptly decreased.  As the craft continued to turn so that it was viewed from behind, the distance between those lights increased.  The continued increase in relative distance after the craft turned is due to the craft moving closer to the camcorder.  In other words, the orientation of the craft was independent of its direction of movement.  The maximum width at the right represents where the craft momentarily stopped before reversing direction.  Accompanying that change in direction, turbine whining increased substantially in both volume and pitch (upwards to higher frequencies).

Note how the shape of the curve resembles the silhouette of a mantaray or shark, with the mouth represented by the green area.

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Sounds

The same sound clip was resampled at 16,000 Hz (moderate quality) and at 8,000 Hz (fair quality) from its original 48,000 Hz sample rate.  The lower sampling rates reduced the high frequency background noises and distorted the sounds, but that was necessary in order to control file size for internet downloading. 

Shorter segments containing mostly engine noises.
20aug03g.wav (691 Kb, 9:41:00 pm to 9:41:23 pm)      20aug03h.wav (450 Kb, 9:41:45 pm to 9:42:00 pm)

Long clip containing above segments (9:41:00 pm to 9:42:02 pm)

download 1
1,673 Kb (16 kHz resampling)

20Aug03d

download 2
837 Kb (8 kHz resampling)

20Aug03e

The frequency spectrogram shows four groups of sound.  Only the lowest group between 0-2 kHz came from the Manta Ray.  All the other frequency bands above 2 kHz represent background noise, determined from a control sample (see spectrogram below).  The Manta Ray produced four separate frequency bands, one of which increases in pitch as the craft began to move away from the observers.  The reversed Doppler effect seen in sounds from other Manta Ray recordings is not evident in this performance.  Within the higher frequency bands distinctive chirps can be seen, which probably represent a cacophony of cricket chirps in the background.  Above 9 kHz cricket sounds stand out.  At 11,200 Hz resampling rate these chirps sound like the slaps of a rotar blade on a helicopter.  Helicopter blades produce chops about 11 times a second (see spectrogram at bottom of page), which is similar to that of the cricket sounds.  However, helicopter sound resonates through all frequencies from 0 to 12 kHz, whereas the cricket sounds in the Manta Ray and control spectrograms occur above 2 kHz (resolved only above 5 kHz), ruling out a helicopter source.

The frequency spectrogram below was taken from a recording at 48,000 Hz digital sampling rate; it represents the the time when the Manta Ray was closest to the microphone.  Note the high pitched cricket sounds between 7 kHz and 16 kHz.  In the control sample below this spectrogram, those cricket sounds are much louder, because the microphone was close to a cricket source.  All the sounds made by the Manta Ray fall below 2 kHz.

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Control sample taken after the Manta Ray was gone in order to show background sounds; 48,000 Hz digital sampling rate.  Low frequency sounds with vertical tails represent the shoe thumps of two people walking through the grass.

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Helicopter spectrogram below.

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This web page was created on 24 August 2003.
It was last updated on 12/18/2011

Bruce Cornet 2003

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