13 replies to this topic

[alcyone00]

Yesterday I was looking at aurora photos that happened last month during perseid shower and noticed some strange trails that I can't figure out what created them. I've been doing astrophotography for a few years now and I can identify airplanes, satellites and meteors but this doesn't make any sense to me.

 

- It was a timelapse sequence without any pause between frames

- Each frame is 13 seconds. ISO 3200 and f2.8.

- Canon EOS R8+Canon RF 35mm 1.8 lens.

- Camera was on tripod.

- Trails are mix of red and blue, as far as I know airplanes are using red and green but if it was a plane it would appear on more than 1 frame.

- Location is eastern Croatia in the middle of a field.

 

Here are cropped images without any edit but I will also provide link to raws.

 

 

Red / blue and not straight line?

 

 

 

Now for a more interesting part, I exported frame before and frame after so 3 frames from timelapse, trails only appear on one of them BUT on frame before there is a tiny dot and a line which are not on other frames, it's like object was stationary on first frame, on second frame it created trails and gone on the last frame.

You can see on this crop that line and dot (it's not a star) are aligned just like the trails that appear on next frame

 

 

 

Also another interesting thing if you zoom between those two vertical trails you can see 2 dots that appeared, on previous and next frame they are gone so it's not a star.

 

 

Link to 3 frames side by side:

 

https://imgur.com/a/f59aY3j

 

Link to full resolution crops and CR3 raws:

 

https://drive.google...8qe?usp=sharing

 

I would appreciate if someone can check those raws and analyze it more because I can't figure it out. Did someone ever saw trail like that?

 

 

 

 

[t-ara-fan]

The red+blue is actually red, blue, and often green.   This is a very small light source that is moving across the Bayer matrix on your sensor. You have very good focus and optics, so the point spread function of the light source is so small it is just hitting one pixel at a time.

 

Stationary? No.  The light source was just on briefly.  If it was stationary and on for 10+ seconds, it would be much brighter (bigger spot on the sensor).

 

In the first pic, there are two trails. Is that one exposure? 

 

Definitely an unusually thing you are seeing.  It could be space junk. Rotating, so sometimes it is illuminated for a few seconds, sometimes it is not reflecting any light, and a few momentary flashes that cause the points of light.

Edited by t-ara-fan, 19 September 2024 - 10:03 PM.

[alcyone00]

The red+blue is actually red, blue, and often green. This is a very small light source that is moving across the Bayer matrix on your sensor. You have very good focus and optics, so the point spread function of the light source is so small it is just hitting one pixel at a time.

Stationary? No. The light source was just on briefly. If it was stationary and on for 10+ seconds, it would be much brighter (bigger spot on the sensor).

In the first pic, there are two trails. Is that one exposure?

Definitely an unusually thing you are seeing. It could be space junk. Rotating, so sometimes it is illuminated for a few seconds, sometimes it is not reflecting any light, and a few momentary flashes that cause the points of light.

Yes it's one exposure, 2 trails appeared and some dots between them if you zoom it.

[JohnTMN]

Star link,,(.)

[t-ara-fan]

Yes it's one exposure, 2 trails appeared and some dots between them if you zoom it.

In that case, like John said: Starlink.

[alcyone00]

In that case, like John said: Starlink.

But why is it only on one frame, it's only 13 sec exposure and completely gone on next frame which means they traveled that distance in less than 13 seconds. I usually have satellites on multiple frames and you can see them traveling across the sky.

[LeoUK]

But why is it only on one frame, it's only 13 sec exposure and completely gone on next frame which means they traveled that distance in less than 13 seconds. I usually have satellites on multiple frames and you can see them traveling across the sky.

You can't assume that it's the same object. It might be, or it might not. Either way, satellites can go from easily visible to invisible for a number of reasons. Many satellites are usually invisible until they catch a reflection from the Sun just right, which is known as a "flare" or "glint".

 

Those who build satellites are usually keen to reduce the reflectivity of the satellite, but satellites often have some highly reflective surfaces like antennas, which can result in a satellite brightening by a few magnitudes when the angle between Sun, satellite, and observer/camera are just right. This means that many satellites are effectively invisible the vast majority of the time, except during a flare/glint.

[JohnTMN]

But why is it only on one frame, it's only 13 sec exposure and completely gone on next frame which means they traveled that distance in less than 13 seconds. I usually have satellites on multiple frames and you can see them traveling across the sky.

Star link trains, are programmed/manipulated to expand and rise after deployment. (deployment happens after launch). They change position and move from view within a few days.

Do a little research on/about Elon's Star link project. The info easily available and is a bane to star gazers across the globe.

[Jon Isaacs]

You can't assume that it's the same object. It might be, or it might not. Either way, satellites can go from easily visible to invisible for a number of reasons. Many satellites are usually invisible until they catch a reflection from the Sun just right, which is known as a "flare" or "glint".

 

Those who build satellites are usually keen to reduce the reflectivity of the satellite, but satellites often have some highly reflective surfaces like antennas, which can result in a satellite brightening by a few magnitudes when the angle between Sun, satellite, and observer/camera are just right. This means that many satellites are effectively invisible the vast majority of the time, except during a flare/glint.

 

Given the linearity of the path and the length of the trails, I think it's a pretty safe assumption that it is a single object that is probably rotating. 

 

The Starlinks I have seen are constant brightness. 

 

If you know the time and date, you can look up the satellites in apps like SkySafari.

 

Jon

[Peter B]

Drone?

[alcyone00]

Given the linearity of the path and the length of the trails, I think it's a pretty safe assumption that it is a single object that is probably rotating. 

 

The Starlinks I have seen are constant brightness. 

 

If you know the time and date, you can look up the satellites in apps like SkySafari.

 

Jon

I also doubt its starlink, doesn't match any starlink trails I saw online. I have time and date but it was last month so I don't know if it's possible to "rewind" that long?

[LeoUK]

I also doubt its starlink, doesn't match any starlink trails I saw online. I have time and date but it was last month so I don't know if it's possible to "rewind" that long?

I'm not convinced it's starlinks either (my comments above were just for information purposes).

 

I would say, did you catch any other satellites in this series of images, and if you did, did they have as much colour in them as the trail in question, or were they just white?

 

The colour in the trails does strike me as a bit odd, but I thought perhaps it might just be something to do with the camera.

 

I think Peter might be close with his suggestion. Note the roundness of the two dots you pointed out in the OP. To me those look like strobes, so probably a drone or aircraft I would say is most likely.

[LeoUK]

The Starlinks I have seen are constant brightness.

That is not always the case. I have seen them flaring on many occasions. The OP of this recent thread has a timelapse showing them flaring, and if you scroll down a bit to my own post there, I've posted some real-time footage one of my own cameras caught for comparison/to clear up some confusion. While it's only a short section of footage, I should note that the entire event lasted a few minutes, but pointless uploading minutes worth of more of the same (plus 4k footage quickly eats up my limited data allowances!).

[alcyone00]

I'm not convinced it's starlinks either (my comments above were just for information purposes).

 

I would say, did you catch any other satellites in this series of images, and if you did, did they have as much colour in them as the trail in question, or were they just white?

 

The colour in the trails does strike me as a bit odd, but I thought perhaps it might just be something to do with the camera.

 

I think Peter might be close with his suggestion. Note the roundness of the two dots you pointed out in the OP. To me those look like strobes, so probably a drone or aircraft I would say is most likely.

Yes, there are multiple satellite captures from this series. Here is one example, top left corner.

 

https://i.imgur.com/kIUNioA.jpeg