Unusual Light Track in Long Exposures, Grand Canyon

[Mick West]

I was in Arizona on the south rim of the Grand Canyon taking pictures of the milky way and captured this image July 6th at 10:13-22". In the 10 plus years I have been shooting the night sky I have never seen anything like it. It doesn't look like any plane I have ever seen, it's not a satellite nor a meteor. It is not a bug, so what is it? It is also in the next picture taken 3 minutes and 9 seconds later. I'm pretty sure there is an explanation, I just don't know what it is. Any ideas?

Joel Coombs

Source: https://www.facebook.com/groups/ufoupdates/permalink/10156114585271790/

July 6th at 10:13PM is July 7 4:15AM UTC (assuming Arizona MST). The photo is looking South, at the Milky Way and Jupiter.

The motion and the timing (remember two photos, with long exposures) looks very like a plane flying away to the South East , but what's odd is that it's solid white, as if the entire wings was brightly lit.

 

[Mick West]

Joel sent me the raw files. EXIF:

Device NIKON D850 (NIKON CORPORATION)
Lens Nikon AF-S Zoom-Nikkor 14-24mm f/2.8G ED
Photo Date 2019:07:06 22:13:22
Focal Length 14.0 mm
Aperture ƒ/3.2
ISO 6400
Exposure Time 20 s

Photo Date 2019:07:06 22:16:31
Focal Length 14.0 mm
Aperture ƒ/3.2
ISO 6400
Exposure Time 20 s

 

[Mick West]

Color enhanced. Consistent with red/blue lights on a plane flying away, and some strobes.

 

[Mick West]

Time might be PDT

 

[Z.W. Wolf]

It's not unusual for landing lights to illuminate the underside of an aircraft.

This mysterious object is a 737. (My own photo.)

However in the OP photo:

-Lights are illuminating the wings from wingtip to wingtip
-The reflected strobe is also illuminating the wings from wingtip to wingtip

Or more properly, there seem to be two out of phase lights - one white strobe and a red rotating beacon. The strobe consistently illuminates the wings from wingtip to wingtip and the rotating beacon illuminates most of the wings. I don't think it's credible that a strobe would be able to illuminate the wings like this on a large aircraft.

So most likely this is a small plane at a relatively low altitude. So far my best guess is that this a small - low wing- plane on approach to Flagstaff Pulliam Airport to the south.

What I don't understand is, small airplanes typically have a single landing light on the nose or the front landing gear, or one or two in the leading edge of wings. Why are the wings fully illuminated? A custom logo light on a Grand Canyon air tour plane?

Another reason to think it's a small aircraft. It has a single white navigation light on the tail. As you can see in my photo of a 737 heading away from the camera, there are bright white navigation lights on the trailing end of the wingtip. What we see in the OP photo are the green and red navigation lights on the wings; not overwhelmed by trailing white lights. All airliners have bright white navigation lights on the trailing end of the wingtips. Small planes often have a single white navigation light on the tail; which this plane has.



There are wing inspection lights

Wing inspection lights are mounted on the side of the aircraft fuselage, just forward of the wing root. They are aimed rearward to illuminate the leading edge and top of the wing. Their primary function is to help the crew and maintenance personnel inspect the wings for ice, snow, or damage. The lights are also effective for collision avoidance.

But I don't think the lights in the OP photo are that.

 

[Trailblazer]

Do we know the exact location of the photos? At that time, Jupiter (which appears to be the brightest "star" in the sky) was virtually due south (sky chart centred on Tusayan AZ)

 

[jarlrmai]

Color enhanced. Consistent with red/blue lights on a plane flying away, and some strobes.
View attachment 37717

The shape of the lights and width of the trail is consistent with the diamond shaped distortion/trails on the stars. It's a pretty well stabilised long exposure astro photograph so the shapes are well defined.

 

[Mick West]

I think it's possible the red and green navigation light might just be chromatic aberration, as there are similar colors on nearby stars

The shape of the lights and width of the trail is consistent with the diamond shaped distortion/trails on the stars. It's a pretty well stabilised long exposure astro photograph so the shapes are well defined.

This is a bit confusing though as you'd think the star streaks would be motion of the rotation of the sky. But that would not affect a trail. Nor would it make diamond shapes.

So I think it might actually be just lens distortion, or in fact something like radial blur or radial distortion.

Looking at the raw image, the star "trails" seem to point towards the center of the image, which is roughly pointing south, so you'd expect the starts to rotate around the center.

I think the fact that the lens is 14mm (Nikon AF-S Zoom-Nikkor 14-24mm f/2.8G ED) might be something to do with this. The ultra wide angle minimizes star trails, as they don't move much over 20 seconds

 

[Mick West]

So I think it might actually be just lens distortion, or in fact something like radial blur or radial distortion.

And actually Joel mentions this, and points out that the diamond shapes in the trail are different to the diamond shapes of the stars.
https://www.facebook.com/groups/ufo...10156114864921790&comment_tracking={"tn":"R"}

a few things. the axis is not the same. most of the blur with the stars is actually vignetting from the lens.

 

[Mick West]

the diamond shapes in the trail are different to the diamond shapes of the stars.

Which I think is a result of the shape of the stars being a combination of lens distortion AND the rotation of the sky. Here's a rough fit of the celestial sphere

The celestial sough pole is well below the horizon on the right, but you can see the lines of travel of the stars go around it. Where the light trail is, the direction motion parallels the swept shape of the stars.

 

[deirdre]

@Mick West I cant tell if you already said this.. or which quadrants on your grid there you took these from.. but since these two look the same, are the grid shapes the same where these 2 closeups are from? (hopefully that makes sense)

 

[Mick West]

@Mick West I cant tell if you already said this.. or which quadrants on your grid there you took these from.. but since these two look the same, are the grid shapes the same where these 2 closeups are from? (hopefully that makes sense)

There are from under the magnified section, towards the outer corner.
With the upper right, I think the star field motion is aligned with the lens distortion, so you get a streak. In the lower left the star field motion is at an angle to the lens distortion, so you get a rhomboid.

 

[deirdre]

There are from under the magnified section, towards the outer corner.
With the upper right, I think the star field motion is aligned with the lens distortion, so you get a streak. In the lower left the star field motion is at an angle to the lens distortion, so you get a rhomboid.
View attachment 37723

oh I see. this bit here... ??

 

[Z.W. Wolf]

I don't know how vignetting would distort the shape of multiple point sources of light. That makes no sense to me at all. Vignetting is a reduction in brightness toward the edge of the frame in a circular pattern.

 

[Mick West]

I don't know how vignetting would distort the shape of multiple point sources of light. That makes no sense to me at all. Vignetting is a reduction in brightness toward the edge of the frame in a circular pattern.

Yeah, I don't think that's the right word, however there IS a kind of radial distortion.

 

[Z.W. Wolf]

Yes there is, but I don't know what would cause it. Some kind of diffraction effect?

Your idea of chromatic aberration causing the phantom red and green navigation lights seems sensible to me. I'm still convinced it's an aircraft with a white strobe, a red rotating beacon and steady white lights illuminating at least a part of the body and/or wings of the aircraft. Eliminating the red and green navigation lights eliminates the idea that the lights are illuminating the wings from wingtip to wingtip. So it may be a large plane after all.

In the second OP photo there are two other aircraft streaks.

So I'm going to say it's a distorted image of an airliner with landing lights on.

 

[Trailblazer]

I can't see any obvious candidates at that time on Planefinder, but it would be helpful to pin down the exact location. As others have said it may be a small plane that wouldn't show up on flight radar sites.

 

[jarlrmai]

I looked into aberrations and astro-photography and it looks like some sort of astigmatism as well as chromatic aberation. Some light sources seem to exhibit coma aberation as well.

"Astigmatism causes point light sources at the edge of the frame to appear to stretch in a line."

"Tangential astigmatism spreads point light sources in lines that seem to radiate from the center of the image"

Source:

https://www.lonelyspeck.com/a-pract...rations-and-the-lonely-speck-aberration-test/

 

[AmberRobot]

I looked into aberrations and astro-photography and it looks like some sort of astigmatism as well as chromatic aberation. Some light sources seem to exhibit coma aberation as well.

"Astigmatism causes point light sources at the edge of the frame to appear to stretch in a line."

"Tangential astigmatism spreads point light sources in lines that seem to radiate from the center of the image"

Source:

https://www.lonelyspeck.com/a-pract...rations-and-the-lonely-speck-aberration-test/

Most optical aberrations increase with field angle, so the edges of your photo are typically where you'll see the worst image quality.

 

[Mick West]

it would be helpful to pin down the exact location.

https://www.facebook.com/groups/ufoupdates/permalink/10156114585271790/?comment_id=10156114871036790&reply_comment_id=10156117902581790&comment_tracking={"tn":"R"}

35 54' 03.60" N 113 51' 40.60" W. The camera was where the line starts and pointing ingredients the direction of the arrow. North is directly up

 

[Z.W. Wolf]

This puts a different face on this. This is in the so-called West Rim Grand Canyon area. This is on private land (Hualapai Indian Reservation) and is far to the west of the national park. The aircraft is heading to the southeast, in the general direction of Phoenix. But Phoenix is 190 miles from the camera location, which I think is too far for this to be an aircraft on approach. But the Grand Canyon West Airport is only a few miles away.

This may be an aircraft taking off. Rather than a large jet it may be a midsize air tour prop aircraft.

A candidate may be the common de Havilland Canada DHC-6 Twin Otter Vistaliner

The Twin Otter has three landing lights. The light on the front landing gear is more properly called the taxi light. There is one landing light on the leading edge of each wing.

This is a Twin Otter taking off at night.


The middle light (taxi light) goes out as the landing gear is retracted. But the right wing landing light is still visible even though the plane is headed away from the camera. [timestamp 3 min] Why?

Because the lights are shining through the props.

The propellers are illuminated by the landing lights in the wings. The taxi light in the front landing gear is illuminating the bottom of the nose.

Side view

Rear/side view
The taxi light is gone. We can't see the left prop. The second white light is the white navigation light on the tail. Notice that the rotating red beacon is brighter than both the illuminated prop and the white navigation light; just as it is in the OP photo.

If the plane were farther away from the camera, we could see the illuminated left prop as well.


It's just possible the plane in the OP photo has a logo light - an illuminated tail. But I have no evidence that any of these tour planes have logo lights.

So, just a candidate, but a better one than a noisy jet. The Otter is a turboprop and much quieter.

 

[Z.W. Wolf]

In this scenario a possible candidate would be an air/ground tour from Phoenix.

Something like this

https://www.westwindairservice.com/tours-from-phoenix-scottsdale

From Phoenix - Flight Code: (ADV)
Rates
Adult (Ages 13+): $699.00
Child (Ages 2-12): $630.00

Minimum 2 passengers with surcharge or 3 passengers without surcharge

Duration
6-7 Hours

Highlights

• Scenic, narrated flight from Phoenix to the West Rim of the Grand Canyon
• Helicopter to the bottom of the canyon
• Pontoon boat ride on the Colorado River
• Entrance to the Glass Skywalk
• Time to explore the Indian Village
• Guano point for lunch and a 'walkabout' out to the high point
• Services of your pilot/guide throughout the day to ensure everything runs smoothly

This company operates Cessnas, so it's not this one.

Grand Canyon Scenic Airlines flies Twin Otters. They have short tours that begin and end at Grand Canyon West Airport. They also have air/ground tours that start at 11:30 a.m. from Boulder City, but they also arrange customized charter flights. Boulder City, NV is to the west. The plane in the OP photo is flying SE - but it could turn to the west later. Also, 10:30 p.m. is late for the regular schedule - could be a delayed flight/custom charter?

 

[Trailblazer]

AA1203 flew almost directly over the camera location (circled) at 4.12am UTC (10.12pm local time), at just under 20,000 feet and climbing. That's about one minute before the first photograph was taken.

It was heading almost due east, but if the camera was pointing east of south, that might still check out?

https://planefinder.net/flight/AAL1203/time/2019-07-07T04:10:00.000Z/speed/17

It's listed as DFW-DFW but it actually did a round trip to McCarran airport, Las Vegas.

 

[Trailblazer]

I don't have Google Earth on this computer, but I grabbed the KML file from Flightaware, if anyone wants to play with it.

 

[Z.W. Wolf]

Passed almost overhead but to the north. It wouldn't have been visible to the camera.

 

[Trailblazer]

Passed almost overhead but to the north. It wouldn't have been visible to the camera.

Are you sure? It was a wide-angle shot (14mm lens), which has a horizontal field of view of about 104 degrees (AFAIK the D850 has a full-frame sensor, i.e. with no crop factor, so the FOV will be the same as for a 35mm film camera).

If the camera was pointing east of south (about 28 degrees east of south according to the photographer's diagram, i.e. a bearing of 142 degrees, then the left-hand edge of the photo would be just about due east (142- (104/2) = 90).

Of course, we don't know how precisely accurate flight tracks are out in the desert with few transceivers around...

 

[Z.W. Wolf]

I see what you're saying. Perhaps make a diagram.

 

[Z.W. Wolf]

If I'm doing this right, you may be right.

But if so, why the bright lights? They just forgot to turn off the landing lights?

 

[Trailblazer]

Somebody with the knowhow needs to do a simulated ground view from the camera location with the KML track superimposed. I could but I won't be on my home computer till tomorrow. @Mick West ?

 

[Z.W. Wolf]

This is what an Airbus A321 looks like at night, with the lights on. The engine nacelles are illuminated by lights on the side of the fuselage, there are some other lights that illuminate the underside of the fuselage, and logo lights on the tail.

 

[Mick West]

Somebody with the knowhow needs to do a simulated ground view from the camera location with the KML track superimposed. I could but I won't be on my home computer till tomorrow. @Mick West ?

Well at first I thought it was going in the wrong direction, as it is to the Norht, but then put in the horizontal FOV for a 14mm full frame camera (104.3°) and I tilted the camera up to match the horizon, and the direction of the track changed!

I was quite surprised. Makes sense though with the very wide angle.

Not a perfect match, however the lens is not a perfect rectilinear lens like Google Earth, so a very reasonable match.

KMZ attached

 

[Z.W. Wolf]

A low resolution photo of an Airbus A321 with the lights on.

 

[Mick West]

Setting time to 10:13:30 gives a near perfect match for location

I think we have a winner!

 

[Mick West]

Google Earth has a mode where you can see the stars. It's not that good though, and the time seems to ignore time zones, so gets things in the wrong place. So I made a composite. (time here is MST, so really 10:14)

 

[AmberRobot]

Wide angle lenses typically have lots of barrel distortion. This would likely change the direction of the track significantly.

 

[Z.W. Wolf]

So it seems that they fly the Airbus with these lights permanently on.

They're not landing lights. They're purely cosmetic, or for style... whatever you'd call it.

 

[Mick West]

Landing lights are frequently left on while climbing. At this point it was about 17 minutes into the flight, climbing though 25,000 feet, heading for a cruise altitude of 33,000 feet. So it would not be unusual for the lights to be on.

 

[Z.W. Wolf]

I made an incorrect assumption. The lights illuminating the engine nacelles are not cosmetic, they are a type of inspection light: the "wing and engine scan lights."

This explains everything: What lights are on an Airbus




https://community.infiniteflight.com/t/when-to-turn-on-the-landing-lights/180827/5

In the Airbus they [the landing lights] drop down, so typically we use they for a bit of extra drag. ie If I'm trying to regain profile the landing lights give me a few extra Hundred fpm in the decent. Typically we retract them once the flaps are retracted as with higher speeds because the landing lights can start to cause a vibration in the cabin which is annoying.

 

[Stefan Leahu]

If you've seen them often enough, it's relatively easy to distinguish them from other stuff. They're a bit shivery (but not really like the scintillation you see in stars), and have a different color than, say ,a bright star rising above the horizon. I live around 80km away from a pretty busy airport and I see them often enough. It's true that they often leave them on for quite some time after take-off