Unidentified Flying Object Over Amsterdam

Stacking of 50 images of the flying object, taken between 23:28 (21:28 UTC) and 11:30 (21:30 UCT) with the Spinel UC20MPE sensor and a 85mm F2 Nikon objective. X3 magnification

In order to use a webcam for night shot for astronomical purposes, we purchased a Spinel UC20MPE sensor, with a nominal sensitivity of 0.001 lux. This sensor turned out to be extremely powerful, managing to shoot stars invisible to the naked eye with the small standard objective (wide angle).

The Spinel UC20MPE sensor with its small standard objective (wide angle)
The Spinel UC20MPE sensor with its small standard objective (wide angle)

To be able to use this sensor even for “deep sky” shots, we have developed a software that allows the sum of multiple frames in real time in order to extend the limited exposure time normally allowed by this type of sensors. This sensor in particular has the ability to reach up to 1 second of exposure, where normal webcams typically reach a maximum of one tenth of a second. The aforementioned software is therefore expressly designed to be able to extend this limited display capacity, thus making it possible to shoot objects that are normally invisible in normal filming using standard software’s.

Our Setup, composed of the Spinel UC20MPE sensor with its custom-made adaptor calibrated to work with Nikon objectives, in this case couples with a 85mm F2 objective
Our Setup, composed of the Spinel UC20MPE sensor with its custom-made adaptor calibrated to work with Nikon objectives, in this case couples with a 85mm F2 objective

Obviously, given that our interest is purely astronomical, we have created an adaptation to be able to use photographic lenses with Nikon mount in order to be able to use much more powerful optics than the standard lens…

On the evening of August 9th, we were preparing to test a newly purchased objective, a Nikon 85mm F2 to verify its optical quality and accurately determine its performance in conjunction with Spinel’s UC20MPE sensor.

Given the focal length of the lens, we immediately realized that without any equatorial tracking adding more than 2 frames with our software wasn’t convenient, a problem that solves as soon as possible adapting it to a telescope already mounted on a motorized equatorial mount.

The first results were immediately very exciting; on the monitor it was already possible to see stars of 8th magnitude real-time, despite the presence of the Moon in a sky that was not completely clear!

In the center we can observe Vega, instead, in the upper-left corner we can admire the Epsilon Lyrae, plus other stars of about 8th magnitude
In the center we can observe Vega, instead, in the upper-left corner we can admire the Epsilon Lyrae, plus other stars of about 8th magnitude

We made the first tests by pointing to the Moon itself and Jupiter, of which it was already possible to see at least two moons. Our Moon appeared large enough to be able to appreciate some visible craters on the terminator.

Jupiter and two of its moons, recorded just after sunset, with the sky still bright and Jupiter at only 15° high on the horizon
Jupiter and two of its moons, recorded just after sunset, with the sky still bright and Jupiter at only 15° high on the horizon
Moon recorded at 21:24 (19:24 UTC) while it was only 16.7 ° on the horizon, hence the reddish color
Moon recorded at 21:24 (19:24 UTC) while it was only 16.7 ° on the horizon, hence the reddish color

As soon as the sky became dark enough and the Moon itself approached sunset, we began to shoot the first stars, starting from the constellation of Lyra which was very close to the zenith at that time.

Processed stacking of 81 frames recorded between 00:14 (22:14 UTC) and 00:17 (22:17 UTC) on August  10th. The photo depicts the 2 lower stars of the constellation of Lyra, centered approximately on the annular nebula M57, visible here as a newly dilated point
Processed stacking of 81 frames recorded between 00:14 (22:14 UTC) and 00:17 (22:17 UTC) on August 10th. The photo depicts the 2 lower stars of the constellation of Lyra, centered approximately on the annular nebula M57, visible here as a newly dilated point

Wonder and awe at the number of visible stars and the Epsilon Lyrae perfectly resolved into two clearly separated stars. Suddenly at around 11:28 pm (Daylight Time 21:28 UTC) we noticed the presence of an object that moved between the stars in an easterly direction. Enthused by enthusiasm, we immediately started recording, succeeding in capturing 50 usable frames of the moving object; further attempts to re-position the object after leaving the camp have unfortunately failed. The sequence where the object is recorded lasts 100 seconds, each frame being the sum of two frames of 1 second exposure, for a total of 2 seconds of exposure per frame. The object was totally invisible to the naked eye and showed, in the images taken, a singular shape consisting of two blue luminous points joined by an arc of light also bluish in color but less luminous than the two points themselves, the apparent motion was extremely slow and therefore definitely not attributable to an airplane, which also would have had to flash. The direction and angular velocity are more typical of a satellite in a medium-low orbit, but the aspect definitely does not agree with this hypothesis. Moreover, at the moment none of the known satellites was flying over Amsterdam.

31st picture of the flying object taken at 23:29:25 (21:29:25 UTC) with an exposure time of 2 seconds. Unprocessed picture
31st picture of the flying object taken at 23:29:25 (21:29:25 UTC) with an exposure time of 2 seconds. Unprocessed picture

Therefore, it was impossible to identify the object itself, whose nature at the moment remains unknown to us! However, given the peculiar nature of such a phenomenon, we have decided to publish the material at our disposal for the benefit of anyone who wants to see it or is even able to explain its nature.

Using a stacking program for astronomical use (Registax), we superimposed all 50 frames following two different processing lines. In the first case we added the frames, keeping the stars aligned, so that we could accurately identify the area of sky that we had taken. This turned out to be just below Vega, at the same height as Zeta Lyrae, which in fact appears in the ‘last frames’ as the brightest red star that enters the frame from the left side of the image. In this elaboration it is even possible to see stars around the 9th magnitude.

Raw stacking of the 50 frames taken; the reddish star on the left side is Zeta Lyrae
Raw stacking of the 50 frames taken; the reddish star on the left side is Zeta Lyrae
Processing of the image above cropping the central part, recorded in each frame.
The small glow in the middle of the left side is given by Zeta Lyrae, while the other glow in the upper side is caused by Vega, located just outside the frame
Processing of the image above cropping the central part, recorded in each frame. The small glow in the middle of the left side is given by Zeta Lyrae, while the other glow in the upper side is caused by Vega, located just outside the frame
Stellar reference map of the recovery area. In the lower left corner, it is possible to read both the altazimuth and equatorial coordinates of the area where the object passed; as you can see, we were only 15 ° from the zenith
Stellar reference map of the recovery area. In the lower left corner, it is possible to read both the altazimuth and equatorial coordinates of the area where the object passed; as you can see, we were only 15 ° from the zenith

In the second elaboration, stacking was carried out following the object itself, in order to be able to improve the quality of the image of the object to the maximum and be able to study it in more detail. The doubt was that, by increasing the visibility of invisible dark details in the individual frames, we could better observe its morphology and maybe be able to identify it. Unfortunately, despite the quality of the processing thus obtained, we have not been able to associate its form with anything we know.

Raw stacking of the 50 frames aligned on the flying object
Raw stacking of the 50 frames aligned on the flying object
3X digital magnification with interpolation of intermediate pixels, without further processing
3X digital magnification with interpolation of intermediate pixels, without further processing
Stretching of the brightness and increase of the micro-contrast of the previous image, in order to make even the weakest areas visible in the raw image easily visible
Stretching of the brightness and increase of the micro-contrast of the previous image, in order to make even the weakest areas visible in the raw image easily visible
Technical specifications of the UC20MPE sensor
Technical specifications of the UC20MPE sensor

Its singular shaped resulted in two luminous arches that joined the two points of light, of which the one farther east was definitely the brightest, all forming a sort of a singular ‘old telephone handset’.

Let’s now enter into the specific technical characteristics of our setup, as well as of the astrometric measurements calculated on the images obtained. The sensor in question consists of a matrix of 1920 x 1080 pixels, each with a size of 3 μm.

Coupled with the Nikon 85mm F2 objective, a scale of 7.27993 arcsec / pixel is obtained, Area framed = 3 ° 52′ 57.47″ X 2 ° 11′ 2.33″.

In Amsterdam at 11:28pm (time of beginning of the recording) the Sun was at about 15.8° below the horizon. This means that the “object” should have been at least at 250.23 km of altitude to be illuminated by the Sun.

The distance between the two points resulted to be about 11 pixels corresponding to 80″. Analyzing instead the luminous halo between and around the two points, this had a size of around 58’’ X 124’’ for the brightest part, while in total the halo extended for 204’’ X 298’’.

Another important parameter detected by the sequence is the angular motion; we must keep in mind two types of motion, that is the motion observed by the observer with fixed aiming and the movement relative to the background stars. In the first case, the motion with relative to the observer allows us to calculate its speed relative to the terrestrial surface, while in the second case it provides us with useful indications for the calculation of a possible orbit around the Earth. The angular speed detected in the span of 60 seconds was 706″ relative to the earth’s surface and 1420″ compared to the stars.

Assuming that it is a satellite and taking into account the angular speed relative to the stars, we have estimated that the hypothetical satellite would have made a revolution around the Earth in 15h 12m 56,48729s, on a presumably circular orbit with a radius of 31.176.564km. Taking into account the radius of the Earth, the altitude from the surface should be 24.805,564km.

This hypothesis, however, must be discarded a priori since, at the given distance and given the angular separation of the two light points, these should have been about 9,6 km away from each other; definitely too much for a satellite!

In fact, given the angular distance of the two points (Dp), the distance from the object (Do) it would be 2578.31 times the linear distance between the two points.

Dp = Do / 2578,31

Do (km)Dp (m)
207,757
4015,514
25096,963
24805,5649620,862

Another interesting analysis concerns the angular speed of the object. As we showed above, the angular speed compared to the stars was used to calculate a possible orbit in the case of a satellite; hypothesis, however, discarded for the reasons mentioned above.

Taking instead into consideration the angular speed relative to our surface, we immediately deduce that the distance from the object is 17529,586928 times the speed itself in m/s.

Angular Speed relative to the ground = 706 arcsec/min => 11,7666 arcsec/sec

V = Do / 17529,586928

Do (km)V (km/h)
204,107
408,215
25051,342

If we consider the object as a satellite orbiting around the Earth, calculating its orbit, we obtain an enormous object size and out of reach of our technological capabilities.

Considering instead the object as an aircraft inside the terrestrial atmosphere, these result to have such a low speed to not allow any type of flight; how is it possible to reconcile these two things?

Even taking into consideration the hypothesis of the weather balloon, the high-altitude currents would give it a decidedly higher speed than the one observed, in any case, being considerably outside the area still illuminated by the Sun, it would have been invisible. As announced above, at that time in Amsterdam, the Sun was 15.8 degrees below the horizon, and even if it climbed to 40 kilometers, the Sun would still have been around 10 degrees below the horizon. Under these conditions, even considering atmospheric terrestrial refraction, the object would have been in complete darkness and would therefore be invisible.

Even with the awareness of these in-depth analyzes, the nature of the object remains unknown.

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