If you traced a hypothetical satellite at 160 km altitude, how fast would it be?But that's only the lowest possible speed assuming it moves perpendicular to the observer. When I apply it to that hypothetical plane at 35,000 ft from further above I get a speed of around 950 kts, but the traced path shows it's closer to 1,500 kts. So that's only 2/3 of the actual speed.
Article: Due to atmospheric drag, the lowest altitude at which an object in a circular orbit can complete at least one full revolution without propulsion is approximately 150 kilometres (93 mi).
Yeah it's interesting, the high res download is a video file with dimensions of 2560/1440 which is an odd resolution for a video device
Yeah it's more common as an option these days but it's more of a computer display resolution than a cinema/video standard if that makes sense, generally 'video' devices do 720/1080/4k. It's a moot point now anyway as we had the wrong device anyway.It's not that weird, my phone calls it "3.5MP" mode, using a completely standard 16:9 ratio.
Why not birds: [...] Also, these birds are moving west, not south (hibernation).
Could you ask the witness if the illuminator was turned on? If they were intending to watch the sky, they may have had it turned off, as it wouldn't be of much use, to conserve power.Now birds don't usually carry lights around, but his particular NV device has an IR illuminator with a 654yd (±600m) range, and anything flying within that range, like birds, would reflect the IR light and light up in the NV binoculars.
Article:
Is that the right IR type for the bino's sensor though. Near IR vs MWIR/LWIRCould you ask the witness if the illuminator was turned on? If they were intending to watch the sky, they may have had it turned off, as it wouldn't be of much use, to conserve power.
A bird is warm and will thus show up against a cold sky. The body will obviously radiate more heat than the wing feathers do, which don't have blood vessels in them.
At rest, a bird's wings are close to the body, so the inside=underside starts out warm, but after a bit of flying, the feathers have cooled off.
Article:
My point is that the bird need not be illuminated to be seen in IR, and in that case, the wings would not be expected to be visible.
Why not? Migratory birds have a biological compass that allows them to follow a direction accurately.is it possible birds fly in such a straight line ?
Didn't we hear the the AF returns all eligible sightings in a 48-hour window? They weren't "wrong".did you contacted the Airforce once more about the wrong time they checked in ?
Well i was wondering because in the video it was a very thight and straight line.. i dont remember ( im a nature lover but not realy paying attention to birds alas..) to see birds flying like that. It seems that wind didnt Had an affect on the object.Why not? Migratory birds have a biological compass that allows them to follow a direction accurately.
Birds heading for Africa would be likely to fly South-West from the Wadden Sea to cross the Mediterranean at Gibraltar. Nocturnal migration is common.
Didn't we hear the the AF returns all eligible sightings in a 48-hour window? They weren't "wrong".
They wouldn't make a claim what the object was, and we have the correct times already.
Article: For sustained flight, it may be generally concluded that larger birds fly faster than smaller birds. A common flying speed of ducks and geese is between 40 and 50 miles per hour, but among the smaller birds it is much less.
Article: Birds usually fly relatively low. Most of the year, they stay under 500 feet [150m]. During migration, though, birds gain altitude, and many species fly at 2,000 to 5,000 feet [600-1500m] or higher, using prevailing winds to assist them. A bird may begin migration at about 5,000 feet and slowly climb to 20,000 feet.
On Metabunk, you can't just post links, you need to quote the important content.Here the weather conditions of that night.
https://www.timeanddate.com/weather/netherlands/utrecht/
If you traced a hypothetical satellite at 160 km altitude, how fast would it be?
Article: Due to atmospheric drag, the lowest altitude at which an object in a circular orbit can complete at least one full revolution without propulsion is approximately 150 kilometres (93 mi).
If we can rule this out, we've pretty much ruled satellites out, unless they were burning up on re-entry?
The problem is that EasyMuffin puts the object too fast if at 160km:It is not uncommon for small missions to have a very limited lifetime. And thus it will not last many orbits, or perhaps not even one. And indeed, if they have propulsion on board, of course much more can be done to keep the orbit going. But I agree, 160km is rather low.
I still think we should not rule out spacefaring.
For that to be an orbital speed, the orbit either needs to be highly elliptic, or the object needs to be lower, maybe at 120 km, because that puts it at ~8km/s?So 10+ km/s
The problem is that EasyMuffin puts the object too fast if at 160km:
For that to be an orbital speed, the orbit either needs to be highly elliptic, or the object needs to be lower, maybe at 120 km, because that puts it at ~8km/s?
Which is already close to the Karman line at 100 km, below which an aerodynamic craft is more effective than a rocket. Hmmm.
That's why I suggested a re-entry situation as possibility.
Article: For sustained flight, it may be generally concluded that larger birds fly faster than smaller birds. A common flying speed of ducks and geese is between 40 and 50 miles per hour, but among the smaller birds it is much less.
50 mph ≈ 80 km/h ≈ 20m/s
With 2⁰/s = 0.035 rad/s, 20m/s puts them at a range of 600m. This feels low for bird migration.
Article: Birds usually fly relatively low. Most of the year, they stay under 500 feet [150m]. During migration, though, birds gain altitude, and many species fly at 2,000 to 5,000 feet [600-1500m] or higher, using prevailing winds to assist them. A bird may begin migration at about 5,000 feet and slowly climb to 20,000 feet.
On Metabunk, you can't just post links, you need to quote the important content.
So, not much wind.
If he was wearing it, the diodes would be facing his wrist ;-) I don't see any way in which the diodes could have unintentionally caused an internal reflection that he then tracked himself — especially not considering that binoculars are generally held with both hands.Was was the photographer wearing a Garmin optical HR sensor?
This is an interesting point. I'm no ornithologist, but I believe only migratory birds fly in a V-formation and migratory birds are usually larger than other birds common to this area, like sparrows and blackbirds. Since this footage was shot at 6x zoom, and the birds were flying in a V-formation — thus being larger, migratory birds — we should be able to see wings and movement?If birds though they are high enough that we see no wing flapping detail through binoculars that are quite narrow field, and also what are we seeing of them with this device, enhanced natural light, reflected IR? Both? We'd need them them to be small/high enough to show as points, but then are they moving way too fast?
I think you're confusing IR with thermal vision? In this case, IR mode was ON, meaning an IR bulb in the binoculars was casting IR light, illuminating anything within in its 600m range, and reflecting back to the camera sensor. The footage does not show a heat signature; only surface area.Could you ask the witness if the illuminator was turned on? If they were intending to watch the sky, they may have had it turned off, as it wouldn't be of much use, to conserve power.
A bird is warm and will thus show up against a cold sky. The body will obviously radiate more heat than the wing feathers do, which don't have blood vessels in them.
The witness mentioned he recorded this footage at 6x zoom.It would be helpful to know the zoom level being used on the Binos at the time as they have a range
Nope, but our air force doesn't provide opinions They just provide all flight data they have that match the time/location of the sighting, even when it's off by a few minutes. The fact that they had nothing for that exact time (18:53 UTC) tells us this object was not tracked on radar.@oscaralexander did you contacted the Airforce once more about the wrong time they checked in ?
This is an interesting point. I'm no ornithologist, but I believe only migratory birds fly in a V-formation and migratory birds are usually larger than other birds common to this area, like sparrows and blackbirds. Since this footage was shot at 6x zoom, and the birds were flying in a V-formation — thus being larger,
The witness mentioned he recorded this footage at 6x zoom.
In the first part of the video the object travels its own size in about 0,065 seconds. So size = speed x 0,065.Article: For sustained flight, it may be generally concluded that larger birds fly faster than smaller birds. A common flying speed of ducks and geese is between 40 and 50 miles per hour, but among the smaller birds it is much less.
50 mph ≈ 80 km/h ≈ 20m/s
With 2⁰/s = 0.035 rad/s, 20m/s puts them at a range of 600m. This feels low for bird migration.
Article: Birds usually fly relatively low. Most of the year, they stay under 500 feet [150m]. During migration, though, birds gain altitude, and many species fly at 2,000 to 5,000 feet [600-1500m] or higher, using prevailing winds to assist them. A bird may begin migration at about 5,000 feet and slowly climb to 20,000 feet.
First, please consider that I was looking for a high-end speed to see how far up I could place these if they're birds. They could well be slower and lower and smaller.At 20 m/s the triangle size would be about 1,3 meters. Is that sufficient to accommodate three birds flying in a triangular formation?
Do you still have the time codes for these closeups? Are they in sequence?If you go through the video frame by frame there are a number of frames where the camera motion happens to partially compensate for the object's motion blur. The lights seem to be quite small and distinct in those frames. Would that be expected if they were birds?
If the triangle is flying at a constant height, the laws of perspective demand that its apparent size shrinks in proportion to its height above the horizon. sin(28.5⁰)/sin(40.3⁰)=74%I compared some shots from the video with objects in the sky to determine some bearings,
and mapped the sightlines in Google Earth.Code:Time Azim Elev 20:53:51 122.75 40.30 20:53:57 139.50 35.67 20:54:01 147.75 32.75 20:54:06 158.00 28.50
The Wizzair was at the time of the airforce looked up no where near the location...
With a size of 1,3 meters and an angular size of 0,2 degrees, their distance is just 372 meters. This is well within the range of the IR illuminator. Would we be able to see more in that case, or are they too out of focus for that?600 meters is the stated effective range of the IR illuminator so if we are are saying they are lit by that then they are within/around this distance way, they could be further if they are more reflective to IR than normal.
1.3 meters (if accurate) spread seems pretty tight for some of the birds of the size that would fly in V, I mean it could be 3 small birds just happening to make a regular triangle, is the motion always with a dot forward in the direction of travel?
Ducks as stated might fit
If they are not able to be lit by the IR illuminator then they must be self lit and either be dim and close or distant and brighter to a range of known objects like planes/satellites.
With a size of 1,3 meters and an angular size of 0,2 degrees, their distance is just 372 meters. This is well within the range of the IR illuminator. Would we be able to see more in that case, or are they too out of focus for that?
With a size of 1,3 meters and an angular size of 0,2 degrees, their distance is just 372 meters. This is well within the range of the IR illuminator. Would we be able to see more in that case, or are they too out of focus for that
I do not have the exact time codes but the frames are easy to find if you go through the video frame by frame.Do you still have the time codes for these closeups? Are they in sequence?
If the triangle is flying at a constant height, the laws of perspective demand that its apparent size shrinks in proportion to its height above the horizon. sin(28.5⁰)/sin(40.3⁰)=74%
Are you saying 1.3 meters for the triangle formation i.e. corner to corner? Can we get a size for the triangle at 300 -> 600 meters?
The object constantly blurs due to camera and object movement, atmospheric disturbances, imaging artefacts etc..Someone on the dutch website made a remarkble observation of the video he zoomed in and wrote somehow he could see flapping and believe it could be birds.
I dont know how to insert here the gif he made so im putting the link of the gif. Sorry if it goes against the rules ! Blame it on me.
There is a lot of noise and the gif is up for discussion I think. But i found it interresting how he managed to zoom in so closely.
https://uploads.disquscdn.com/image...00129d39fc264d7ecd057255b75f92bf4ba1efb96.gif
Someone on the dutch website made a remarkble observation of the video he zoomed in and wrote somehow he could see flapping and believe it could be birds.
I dont know how to insert here the gif he made so im putting the link of the gif.
0.2⁰ is a very rough estimate, not an accurate determination; at best, it represents 0.15-0.25⁰. Converting this to a 3-digit number looks like more precision than there actually is.The distance can be derived from its angular size. The angular size of the ‘lights-triangle’ has been determined already and is 0,2 degrees, or 0,00349 radians
Again, 2 frames is a low-precision number, as is the 2⁰/s angular speed I have been working with. The most precise numbers posted to the thread so far are @EasyMuffin's azimuth/elevation data, which is why I've been asking EM to confirm my estimate for the potential satellite speed.The speed can be derived from the fact that the ‘lights-triangle’ travels its own size in about 0.065 seconds (about two frames in the 30 fps mp4)
Thank you Mendel !
At this timecode there are some birds (a big flock of geese, and a 4-ship)
https://www.lunaoptics.com/nvtechnology.html
All of Luna Optics digital day/night vision devices employ various SONY Exmor™ High-Definition CMOS Sensors, which feature low video noise and low power consumption, while providing excellent low-light sensitivity and high-speed image processing. (Exmor is a trademark of SONY Corporation).
What did you ask them?Based on a suggestion over at /r/heavensabove (great idea to consult them!) I've just sent an email to the Dutch foundation for bird preservation. They should be the apex of bird nerds in NL. Will report back when I hear from them!