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  1. Mick West

    Mick West Administrator Staff Member

    MUFON 91964 Metabunk Compare.

    This case of a "UFO" submitted to Mufon, is described as:
    https://mufoncms.com/cgi-bin/report...=f1_submitted_datetime+DESC&case_number=91964
    The first impression was correct. However the resultant photo seems at little confusing.
    Metabunk 2018-05-14 10-05-08.

    The problem is that you naturally interpret this as a set of three lights. But what it actually is is a single light, the red collision avoidance strobe. This is a very bight flashing light, and illuminates other parts of the plane, even in daytime.
    767-beacon-animated.

    In this case it's illuminating the engines.
    Metabunk 2018-05-14 10-08-40.

    Another clue are the two faint bright red spots under the main light
    Metabunk 2018-05-14 10-12-03.
    This matches quite well with the wheel wells of a 737
    Metabunk 2018-05-14 10-14-02.

    The time given is 2018-05-08 8:59PM, that's 2018-05-09 (next day) 2:59AM in UTC. The camera exif time gives the same UTC time - maybe that's common for astrophotography? Looking at that location a likely candidate is SWA1988 from Phoenix to Omaha, which was passing just to the South at 39,000 feet.
    Metabunk 2018-05-14 10-21-17.

    Another thing that throws people off here is the thin lines. These are the long exposure traces of navigation lights, but seem odd as you can only see two of them, and they don't seem to line up with the other lights. However if you look carefully, or just boost the levels, then you can see there actually are three lines.
    Metabunk 2018-05-14 10-29-45.
    What's more the one of the left is green and the on on the right is red, which matches standard wingtip lights.

    They don't line up for a somewhat unintuitive reason - planes do not fly in the direction they are facing. The fly in the direction they are facing at their airspeed PLUS the velocity of the wind relative to the ground. So if there's a crosswind the motion of the plane can be 5° or more off from the direction it is facing.
     

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    Last edited: May 14, 2018
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  2. marrowmonkey

    marrowmonkey Member

    For a minute I wondered why the plane didn't block the stars behind it in the picture (or does it?), but that is of course because it's a long exposure photograph.
     
  3. Robert Sheaffer

    Robert Sheaffer New Member

    Excellent analysis. Looking at that overlay of the plane on the photo, there is no doubt this is what we are seeing.
     
  4. Mick West

    Mick West Administrator Staff Member

    It would be nice to get some video of a 737 doing the same thing. Unfortunately most available video seems to have landing lights on as well, which somewhat obscures the effect. But here's a demonstration of the light illuminating the engines:
    Metabunk-2018-05-14-10-49-49.
     
  5. Mick West

    Mick West Administrator Staff Member

    That's another thing that throws people off, even if they don't really think about it their brains assume it's a small craft because they can see all those stars.
     
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  6. Mick West

    Mick West Administrator Staff Member

    We can tell the direction of the camera because:
    Setting the location, date and time, and searching for NGC4631 gives us:
    Metabunk 2018-05-14 21-12-35.

    Zooming in
    Metabunk 2018-05-14 21-13-39.

    So that's that heading (Az) of 92.5 degrees, and looking up (Alt) at 67°. The plane was at 39,000 feet, so that puts the camera 39000/tan(67 degrees) =16,500 feet to the West of the plane's track
     
  7. Mick West

    Mick West Administrator Staff Member

    But if the camera is looking East, the if we align the photo with the night sky at that time, then it seems to suggests the plane was flying roughly to the West, not the same as the plane I'd identified earlier.
    Metabunk 2018-05-14 22-21-24.
     
  8. Mick West

    Mick West Administrator Staff Member

  9. jarlrmai

    jarlrmai New Member

    Nice work Mick, I love the detective aspect to this.
     
  10. TEEJ

    TEEJ Senior Member

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  11. Astro

    Astro Active Member

    The reflections off the engines are interesting and not something I've captured before, but I do occasionally capture a jet passing through the field of view. Here's a shot from 2013 while I was tracking comet ISON:
    [​IMG]
     
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  12. marrowmonkey

    marrowmonkey Member

    Assuming the galaxy is 10' long as he says, the distance (in arcmin) between the engines is about 3' or 0.04-0.06 deg.
    Az/Alt = 93/67 deg
    Aztec elevation: 5646 ft
    Airplane altitude: 38000 - 39000 ft

    Using the following formula we can get an estimate of what the distance in feet between engines should be:
    v = 2 arctan(x / (2 h))
    where v is the width in angles (degree)
    h distance to airplane in ft
    x distance between engines in ft

    Taking the altitude of 67 deg into account:
    h = (38500-5650) / sin 67
    Assuming no roll or pitch (and a flat earth :)) the apparent distance between the engines is
    x = X sin 67
    where X is the real distance between engines

    this gives us:
    X = [ 2 (39000-5650) tan(0.06/2) ] / [ (sin 67)^2 ] ~= 41 ft
    X = [ 2 (38000-5650) tan(0.04/2) ] / [ (sin 67)^2 ] ~= 26 ft
    best est:
    X = [ 2 (39000-5650) tan(0.049/2) ] / [ (sin 67)^2 ] ~= 34 ft

    I.e. the engines are about 26-40 ft apart.

    From what i can tell the engines on a Boeing 777-200 is about 72 ft apart, but on a Boeing 737 they are 32 ft apart. (I couldn't find particularly reliable data on distance between engines on a boeing 777 though.)

    So the Boeing 737 and flight SWA1988 seems like the best candidate.
     
    Last edited: Jun 19, 2018 at 4:35 PM
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  13. Astro

    Astro Active Member

    Brilliant, wish I had thought of that. Here's the astrometry of his image:
    http://nova.astrometry.net/user_images/2160988#annotated
    Indeed this does confirm the galaxy ID and the coordinates at the center of the strobe light (12hr 42m 29.4s, 32d 36' 25") correspond to an alt of 67.3 degrees and an azimuth of 92.9 degrees at 2:59 UTC from Aztec, NM.
    sin(altitude) = sin(declination)*sin(latitude)+cos(declination)*cos(latitude)*cos(hour angle)
    cos(azimuth) = (sin(declination)-sin(latitude)*sin(altitude))/(cos(latitude)*cos(altitude))
    We can then use the astrometrically solved image to get a more precise reading of the angular separation of the engine reflections:
    http://h.dropcanvas.com/lbgg4/enginesep.jpg
    Looks like your best estimate of 0.049 degrees was just about right on the mark according to my measurement, which as you show above corresponds to ~34 feet part give or take. Not bad.
     
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