Is this a cosmic ray?

Vaeltaja

New Member
Go look at http://heritage.stsci.edu/1999/16/images/raw814_600.jpg for a sample raw HST image. You can see that there are many cosmic rays and there are maybe two or so that are actually reasonably long. So, it's definitely possible to have the ray come parallel through the sensor. But I reiterate that the likelihood seems low that if you only had one cosmic ray in your image it would be one that came through parallel when there are so many more angles available to come through your sensor.
I think there is in every long exposure photo multiple cosmic rays, but typically so weak that they're not visible in the final image, because normal light is so much stronger.

That's why when typically people take photos of cosmic rays they cover the camera so light wouldn't hit the sensor and only the cosmic rays can.
At least that's the way how I understand this.

However, before this thing happened to me I didn't even know that cosmic rays might appear in photos so I'm not an expert of any kind to talk much about this. And I guess its not 100% confirmed to be a cosmic ray anyways. (not sure if it ever can)
 

Mick West

Administrator
Staff member
it is unnaturally in focus. but those 2 big red points (which look like a plane flash), can that be caused by in camera stuff?
Maybe. It could be the ray/particle hitting something at a particular point - like between two pixels, that makes the effect reflect around.

The lack of comparables is big problem here.
 

Trailspotter

Senior Member.
Oh, okay. I can't afford the paid licence for this. I was in Järvenpää when I took the photo.
Thanks for the info. Regrettably, I also have no subscription at the present. That for FR24 is expired, whereas Planefinder was free until recently. The length and apparent elevation of the light trail (estimated as from 30° to 40° above the horizon) is fully compatible with the cruising altitude and speed of a commercial airliner, that would go out of frame in less than 13 second. Lower and slower planes would fit too.
It still would be interesting to check whether there was a plane in that part of the sky at the time or not.

But I agree with the @Mick West argument in post #38, this un-naturally sharp trail is likely a sensor thing.
 

Trailblazer

Moderator
Staff member
Thanks for the info. Regrettably, I also have no subscription at the present. That for FR24 is expired, whereas Planefinder was free until recently. The length and apparent elevation of the light trail (estimated as from 30° to 40° above the horizon) is fully compatible with the cruising altitude and speed of a commercial airliner, that would go out of frame in less than 13 second. Lower and slower planes would fit too.
It still would be interesting to check whether there was a plane in that part of the sky at the time or not.

But I agree with the @Mick West argument in post #38, this un-naturally sharp trail is likely a sensor thing.
I have a FR24 subscription (which I forgot I was still paying for!) and there is nothing I can see in the area. This is the nearest aircraft, assuming Mick has the time zone right, and it doesn't fit with the track at all.

upload_2019-9-2_13-30-59.png
 

Mechanik

Active Member
Cosmic rays appear to be a well-known phenomenon amongst astronomers. The title of this article sums it up nicely: “Cosmic rays and other nonsense in astronomical CCD imagers”. The actual document is paywalled and blocked from cut/paste but the introduction gives you good idea of the content:
https://link.springer.com/chapter/10.1007/1-4020-2527-0_9
Metabunk 2019-09-02 08-10-55.jpg
Another article has a lot of technical details on the problem of cosmic rays striking CCDs as follows:

Link: https://www.bnl.gov/isd/documents/89281.pdf

Somewhere in this doc, it mentions that an exposure of 300-1000 seconds pretty much guarantees that you will have a cosmic ray strike your sensor, so this is a much more common event than I would have expected. Also mentions that muons are the high energy particles that leave tracks like the OP, while the “worms” and “pits” come from particles with much lower energy states. There is even a table in the article that shows a colored pixel track quite similar to the original photo.
Metabunk 2019-09-02 08-15-26.jpg

[Mick: added excerpts and images]
 
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Z.W. Wolf

Senior Member.
So this was probably not caused by a cosmic ray; but by a secondary particle. A muon.

https://en.wikipedia.org/wiki/Cosmic_ray
A singe cosmic ray can cause a shower of secondary particles. So these are more common than might be imagined.
 
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Mick West

Administrator
Staff member
So this was probably not caused by a cosmic ray; but by a secondary particle.
Also referred to as a secondary cosmic ray

https://en.wikipedia.org/wiki/Cosmic_ray
 

Amber Robot

Member
I am willing to concede my point that a long streak cosmic ray
So this was probably not caused by a cosmic ray; but by a secondary particle. A muon.

https://en.wikipedia.org/wiki/Cosmic_ray
A singe cosmic ray can cause a shower of secondary particles. So these are more common than might be imagined.
Yes, detecting air showers is a common way for astroparticle physicists to study galactic cosmic rays.
 

Mechanik

Active Member
Thanks for the edit @Mick West . Don't know whether the issue was the silicon in the iPad, or the carbon poking at the screen.

My first take on this thread was that I thought a cosmic ray would be awesome, but unlikely. Ultimately, this thread is a perfect example of why I visit Metabunk every day. Made me think, do some research, and learn something.

At this point, I’m convinced that this is actually a “much more common event than I’d thought”. Most likely a muon from a higher orbit comic ray strike, happening to pass through the plane of the CCD and then passing out of the plane.

Wikipedia says:

At link: https://en.m.wikipedia.org/wiki/Muon

More (YouTube) research showed that you can build a Cloud Chamber (particle detector) yourself easily using dry ice and (isopropyl) alcohol. YouTube has quite a few videos (the short ones get to the point much faster) and the results are impressive, but with 10,000 muons per minute per meter, I don’t consider this a rare event. The OP was actually fortunate to record the passage of a particle that sleets through our bodies thousands of times every minute, but is only detectable when the particle aligns with the CC. (By the way, I’m not a meter wide so I’m assuming far fewer than 10,000 particle passing thought my body each minute. Still a really large number, though...).

The fact that you can see these in 3D in a cloud chamber, emphasizes that my original thought around how unlikely this even would be, was incorrect. It seems that the low probability of a muon passing through the plane of the CCD is overwhelmed by the huge number of particles that pass though every minute.

I had a hiking buddy who was an airplane pilot and kept track of every minute he was in flight so he could mathematically offset his exposure at flight altitude by averaging that with time spent at sea level and indoors and he KEPT TRACK OF EVERY HOUR spent in the air or at what altitude in what city. My point is that, with that many high energy particles streaming through my body every minute, I can now understand why radiation bothered him. While he may have gone a bit overboard, it’s a bit weird to know how many particles are streaming through my body every minute.
 

Gerard

Member
About 10,000 muons reach every square meter of the earth's surface a minute;
So that's 1 per square cm per minute. You'd think they'd be seen more often in digital photographs. Sure long tracks should still be rare but short ones or single pixel events should happen quite frequently.
 

Gerard

Member
So that's 1 per square cm per minute. You'd think they'd be seen more often in digital photographs. Sure long tracks should still be rare but short ones or single pixel events should happen quite frequently.
Maybe this is due to the phenomenon that the cross section for EM scattering generally decreases with energy so a high energy particle travelling through matter will lose most of its energy near the end of its path. It may be that most of those 10000 muons per minute are very energetic and so have very little chance of actually interacting with anything. The ones you see would then only be a very small fraction that does interact (especially when traversing something as thin as a camera sensor array).
 
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Trailblazer

Moderator
Staff member
Also, a typical camera exposure is of the order of 1/100th of a second (or less in bright light), so if you assume the sensor is 1 square centimetre then even at 1 per minute then you'd only be looking at a one in several thousand chance of a particle passing through a given photograph. And digital photos do tend to have random noise, bright pixels etc, so a single-pixel (or very short track) interaction would likely go unnoticed in a typical photo.
 

Vaeltaja

New Member
I see basically almost in every one of those my long exposure photos some hot pixels, which I nowadays understand are being done by those muons.
 

Gerard

Member
I see basically almost in every one of those my long exposure photos some hot pixels, which I nowadays understand are being done by those muons.
I'm not sure about that. There are certainly other sources of sensor noise. One thing to look at might be if the noise is correlated for different colors of a single pixel. A cosmic ray might be more likely to excite several colors since they're closely spaced. If it's just random quantum noise there probably shouldn't be any correlations.

Also don't forget about non-cosmic background radiation as a source of noise.
 

Amber Robot

Member
I see basically almost in every one of those my long exposure photos some hot pixels, which I nowadays understand are being done by those muons.
Check if they are the same pixels. The term “hot pixels” usually refers to pixels that are always high. Some can be always low or zero and some can have enhanced noise properties.
 
I didn't see anything moving in the sky when I took the photo.
Hi there,

When I saw your long exposure photo and now that I know that you did not see the thingy, this reminded me of a video-capture by Mr Sonota with his WAT-100N (monochrome CCD cam).

I did not check the frame rate of the CCD cam but there's one "spot" visible in frame #00031, could it be a cosmic ray hit?

Capture d’écran 2019-09-07 à 16.39.07.png

Then, what could be a secondary cosmic ray in frame #00032:

Capture d’écran 2019-09-07 à 16.35.02.png


Link to download the video: http://sonotaco.com/sample/etc/e_index.html


Cheers,
Chris
 
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