you should see what cosmic rays do to space telescopes
public almost never sees what raw images look like
RAW https://blog.galaxyzoo.org/wp-content/uploads/2010/04/spiral...
FINAL https://blog.galaxyzoo.org/wp-content/uploads/2010/04/spiral...
* https://blog.galaxyzoo.org/2010/04/12/how-to-handle-hubble-i...
they also slowly destroy the sensors since they are physical particles moving at almost the speed of light
Reminds me of the radiation after Chernobyl causing flashes on the physical film: https://www.youtube.com/watch?v=KOLBEx5DBaE
Can anyone tell whether these exposures occurred through the camera lens (from fallout particles in the sky of the depicted scenes) or in post- (or pre-) exposure handling of the film from hot dust carried by the photographer?
They are not part of the image of the scene. They wouldn't be focused by the optics.
The optics would just be a slight attenuation much like the rest of the camera housing, film reel, operator, etc. So really a summation of all the exposure types you can imagine.
There's no reason they would preferentially travel through the lens and hit the current frame because most of the camera and film housing is about as transparent to gamma radiation as glass. Or maybe more transparent, because glass lenses in pro cameras tend to be rather bulky.
So this just happened somewhere between arrival to and departure from the zone.
thank you so much for this link! I have been trying to search for footage of this phenomenon (in the pre-llm era) 10+y ago
Also the sobering footage taken by this YouTuber by sending a GoPro through a particle accelerator: https://www.youtube.com/watch?v=Uf4Ux4SlyT4
Oh wow, I thought those were stars at first.
thanks for the links, that's really interesting to look at
do you happen to know how exactly those artifacts are cleaned up?
The blog link describes the cleanup process.
They take two pictures, each taking up half the total observation period. If you subtract the two images, the deltas should be the cosmic ray flashes. You can then subtract those out. They use two pictures as opposed to more to minimize the impact of readout noise.
To deal with "stuck pixel" type errors, they can slightly shift the camera between the two observations. They can counter act the shift before doing the initial subtraction.
Signal processing / denoising of astronomical images is a field of study onto itself.
If you are like me you will find it super interesting. There is immense variety based upon what kind of telescope, what do you want to capture, whether it's for science or astrophotography (aesthetics).
If you are into math side of things you can begin with Richardson-Lucy as a starting point and stacking.
funny how this also eliminates "close" fast moving objects. which I guess is a feature for a telescope
I mean funny in the sense of "we did not find any anomalies, because we are careful to filter them out"
One way is to take a “blank” picture which will then show just the noise; then use that as a reference for what can be removed from the image.
The blank should only show long term damage. Hits while the sensor is collecting light can be averaged out from multiple readings of the sensor.
its actually quite doable. any cosmic rays will not be present in two pictures in a row. any permanent damage will be exactly the same in all pictures.
photoshop ;D, or using multiple pictures