Can the aircraft on the attached photo be identified from the light pattern? While photographing this globular cluster (M 13) in Hercules, an aircraft passed through the FOV.

enter image description here

The width between the outer lights is 3 arc minutes and the exposure time was 15 seconds.

The photo was taken on April 23, 2019, 10:28 PM at James River State Park, Gladstone, VA.

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    $\begingroup$ I would be very surprised (and impressed) if someone can 100% identify the aircraft based on this image alone. I assume you have the exact time and location so it's worth checking the history on sites like flightradar24.com $\endgroup$
    – DeepSpace
    Commented Apr 28, 2019 at 17:47
  • $\begingroup$ Please post the specific time and place the photo was taken. $\endgroup$
    – Steve V.
    Commented Apr 28, 2019 at 17:48
  • $\begingroup$ Cool photo! You're not going to be able to identify the plane down to the model by its lights: as I recall, Boeing and Airbus have distinctively different flash patterns from each other but, without knowing the altitude of the plane, you can't tell its size, so you can't get any closer than that. (And, of course, not all planes are made by Boeing or Airbus.) $\endgroup$ Commented Apr 28, 2019 at 17:49
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    $\begingroup$ The photo was taken on April 23, 2019, 10:28 PM at James River State Park, Gladstone, VA. If we know the wingspan of the aircraft, we should be able to calculate its altitude and, perhaps, its speed from the light sequence. $\endgroup$
    – Gary Grew
    Commented Apr 28, 2019 at 18:04
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    $\begingroup$ The only aircraft that appears at the area (23rd April 2019 02:30 UTC) on flightradar24 is a Bombardier CRJ-200LR but I'm not convinced that it's the aircraft in the photograph as it flies at 22K ft according to fr24 but that does not match the wingspan (it should appear much smaller in the photo). So my guess will be a smaller GA aircraft that doesn't have an ADS-B transponder $\endgroup$
    – DeepSpace
    Commented Apr 28, 2019 at 18:30

2 Answers 2


No, based on the exposure pattern I can't identify the aircraft. But based on the other information you gave, I can. It's an Embraer 175, registration N287SY.

After looking up the exact position of the M13 Globular cluster at the time the photograph was taken, I found that the telescope had to be facing to 64 degrees (East-Northeast), with an elevation angle of 28 degrees.

I used in-the-sky.org to find the position of the M13 cluster.

Position of M13

I then drew the geodesic from James River State Park in a heading of 64 degrees I used academo.org to draw the geodesic on the map

geodesic to 64 degrees

Then using Flight radar 24's history/replay function I found the aircraft Aircraft on Flight radar 24

The aircraft is an Embraer 175, flight DL3693, flying at 38000 feet.

If we assume:

  • the telescope is at 500ft MSL,
  • pointing up 28 degrees above the horizon,
  • the atmosphere is ISA, and
  • the earth is flat,

then we can calculate that the aircraft would be approximately 21.5 km horizontally away.

Measuring that out on Google maps gives the following:

Measure distance on the map

That measurement is perfectly in line with the flight path of the Embraer 175.

The slant distance to the aircraft is approximately 24.5 kilometres. The track angle of the aircraft is 228 degrees, so we see the aircraft almost from straight ahead.

The span is 26 meter, I assume the lights are at the wingtips (they are not). The distance between the traces is thus expected to be 3.5 arc minutes. Close enough!

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    $\begingroup$ +1, Well done, mate. $\endgroup$ Commented May 2, 2019 at 0:58
  • $\begingroup$ This doesn't answer the question as asked, but it's so good (and probably answers the OP's real question) that I have to +1 it anyway! $\endgroup$
    – StephenS
    Commented May 2, 2019 at 18:18

All civil aircraft flying at night are required to have navigation lights and anti-collision lights.

Navigation lights comprise a red light on the left wingtip, a green light on the right wingtip, and a white light on the tail. Each should only be visible within about 180 degrees laterally.

Anti-collision lights can be white strobes on both wingtips, a red (or white, for very old light planes) rotating or flashing beacon, or both strobes and beacon. The beacon and/or at least one strobe should be visible from all angles.

Therefore, all planes will look roughly the same at night. If you knew the exact altitude, you could calculate wingspan (from the distance between the navigation/strobe lights) and the ground speed (from the distance it was moving), which may imply the class of plane, but neither measure will be precise enough to distinguish a specific model or even make.

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    $\begingroup$ All modern Airbusses have a double-flashing strobe, most others have not, so some distinction could be possible even based on flash pattern. $\endgroup$ Commented May 2, 2019 at 7:35

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