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As I noted on a similar thread the issue is not removing the streaks, it's what data is lost behind those. If you take a look at this image you'll see that it

As I noted on a similar thread the issue is not removing the streaks, it's what data is lost behind those. If you take a look at this image you'll see that it can be a non-trivial amount of interference in some cases and that data can't just be filled in with "black". https://i.imgur.com/Qdt0N2g.png https://i.imgur.com/Qdt0N2g.png The interference also causes a "glow" effect on the CCD which corrupts the data well beyond the edges of the main streak as well.

ImaCake 6y ago
I guess you could statistically impute that data. But it is the long tail of unlikely readings which are generally interesting, and imputation will not find those.
- SiempreViernes 6y ago
  Imputing makes little sense when you are trying to _measure_ though.
- weego 6y ago
  This is a logic flaw I see everywhere. Making a proposition for what might have been there is not a useful scientific instrument. And especially not when unseen anomalies are an integral part of pushing your field forward. If you're inferring what might have been there you're explicitly filling in based only on what you already know.
  - oasisbob 6y ago
    I agree, but isn't filing in what you already know a common technique when presenting things for human consumption? I'm thinking scanning microscopy, SEM, STM, etc. The image implies that all the data is from the same instant, when it's not. Normally that's OK, but it's not always.
    - Balgair 6y ago
      SEM fills in data?
- Balgair 6y ago
  Unfortunately, the 'glow' is from the optics, not the CCD (you'd see streaks or 'boxing' that way). You can't statistically impute the optics, as these issues are based on physics. A good starter article here; http://spiff.rit.edu/classes/phys312/workshops/w10c/telescopes/telescopes.html http://spiff.rit.edu/classes/phys312/workshops/w10c/telescop...
  - ImaCake 6y ago
    Thanks, that was a fun read. I think I have a better grasp of why you can't impute this now.
0-_-0 6y ago
It seems to be around 1-2%, which I would say is trivial. This can be further reduced if you use multiple exposures because then only 1 contains the streak. Getting satellite data from SpaceX about satellite positions and turning off the receiver for a few seconds would also mitigate the issue. I don't understand how this is treated as a problem that's worth halting satellite launches over.
- vanderZwan 6y ago
  > which I would say is trivial I'm frankly amazed at the arrogance on display here. Do you honestly think you know better then the entire field of astronomy?
  - deleted 6y ago
    [deleted]
  - 0-_-0 6y ago
    You point to saying that 2% is a small part of an image as a sign of arrogance? Isn't it a small part of an image?
    - Swenrekcah 6y ago
      It is a small part of an image, but that does not mean it's not a significant disturbance. Think for instance about CO2 levels. Is it such a big deal if they reach 1% of the atmosphere? It's only a small part after all.
    - dx87 6y ago
      You didn't say it's small, you said it's "trivial". This isn't about people taking pretty pictures, this is about people trying to do actual work. It doesn't matter if it's 1% or 100% if it still ruins what they're working on. So yes, you're being arrogant by saying that just because it's a "trivial" amount that's ruined, when you don't understand what they're doing.
      - 6y ago
dylan604 6y ago
I love all of the comments about using software to filter out the images. This response is so obvious that it is from someone who has never worked with data from imaging the sky, and probably have never thought about it more than a drive-by comment. "Just filter it out" they say. And replace it with what? An average of near by pixels? An AI background replacement? That's just bollocks. Every single dot in the sky is another star, galaxy, planet, asteroid, etc. They are not blemishes in the image. To just write them off would be like drawing a map of the earth without New Zealand on it.
- Balgair 6y ago
  To reinforce this, there is a fair bit of astronomy that is looking for single photon differences. The optics and engineering here is very cool (pun intended) and can take months of time on an instrument to detect, if there is anything at all. Sources of noise are pathologically chased down. Adding in noise would be like trying to chop off your arm, easy to do once, but hard to undo. As a reminder, astronomy is not as much about the 'image' as it is about the 'measurement'. Editing pictures like in Insta is not the point here, you can't fill things in.
  - dylan604 6y ago
    Exactly. Modern day comet/asteroid hunters are taking images from night after night and treating them like time lapses to see what dots are moving. Removing these dots to fill in the void left by the satellite streaks sets this method of detection back to unusable/unreliable. Even filling in the removed satellite streaks in an image with data from previous/next images totally invalidates the tracking of objects in motion.
- verytrivial 6y ago
  .. and I have given up chasing down the 'JuSt UsE SpaCE teLeScoPEs' comments. These people would write off the loss of New Zealand as the market simply finding the right benefit-cost ratio.
crazygringo 6y ago
No, that's not how that works at all. Remember, astronomy images generally have long exposure times, which already involve tracking the sky, and then averaging out values in the exposure across minutes/hours/days/whatever. A satellite passing over a point in the sky means that area of sky is affected for only a tiny fraction of the total exposure. As long as you have a database of all satellite locations, you just don't include data from those time slices in the final average. Or if you don't know where satellites are in advance, you just do basic outlier detection -- the kind that already eliminates things like airplanes, birds, the ISS, etc. Nobody's filling in anything with "black", and the area of satellite interference can be easily expanded to include the "glow" area. In the end, the quality of the overall image is degraded by a tiny fraction of a percentage, which can be trivially overcome by extending the total exposure time by the same tiny fraction of a percentage.

ImaCake 6y ago

I guess you could statistically impute that data. But it is the long tail of unlikely readings which are generally interesting, and imputation will not find those.

SiempreViernes 6y ago
Imputing makes little sense when you are trying to _measure_ though.
weego 6y ago
This is a logic flaw I see everywhere. Making a proposition for what might have been there is not a useful scientific instrument. And especially not when unseen anomalies are an integral part of pushing your field forward. If you're inferring what might have been there you're explicitly filling in based only on what you already know.
- oasisbob 6y ago
  I agree, but isn't filing in what you already know a common technique when presenting things for human consumption? I'm thinking scanning microscopy, SEM, STM, etc. The image implies that all the data is from the same instant, when it's not. Normally that's OK, but it's not always.
  - Balgair 6y ago
    SEM fills in data?
Balgair 6y ago
Unfortunately, the 'glow' is from the optics, not the CCD (you'd see streaks or 'boxing' that way). You can't statistically impute the optics, as these issues are based on physics. A good starter article here; http://spiff.rit.edu/classes/phys312/workshops/w10c/telescopes/telescopes.html http://spiff.rit.edu/classes/phys312/workshops/w10c/telescop...
- ImaCake 6y ago
  Thanks, that was a fun read. I think I have a better grasp of why you can't impute this now.

0-_-0 6y ago

It seems to be around 1-2%, which I would say is trivial. This can be further reduced if you use multiple exposures because then only 1 contains the streak. Getting satellite data from SpaceX about satellite positions and turning off the receiver for a few seconds would also mitigate the issue. I don't understand how this is treated as a problem that's worth halting satellite launches over.

vanderZwan 6y ago
> which I would say is trivial I'm frankly amazed at the arrogance on display here. Do you honestly think you know better then the entire field of astronomy?
- deleted 6y ago
  [deleted]
- 0-_-0 6y ago
  You point to saying that 2% is a small part of an image as a sign of arrogance? Isn't it a small part of an image?
  - Swenrekcah 6y ago
    It is a small part of an image, but that does not mean it's not a significant disturbance. Think for instance about CO2 levels. Is it such a big deal if they reach 1% of the atmosphere? It's only a small part after all.
  - dx87 6y ago
    You didn't say it's small, you said it's "trivial". This isn't about people taking pretty pictures, this is about people trying to do actual work. It doesn't matter if it's 1% or 100% if it still ruins what they're working on. So yes, you're being arrogant by saying that just because it's a "trivial" amount that's ruined, when you don't understand what they're doing.
    - 6y ago

dylan604 6y ago

I love all of the comments about using software to filter out the images. This response is so obvious that it is from someone who has never worked with data from imaging the sky, and probably have never thought about it more than a drive-by comment. "Just filter it out" they say. And replace it with what? An average of near by pixels? An AI background replacement? That's just bollocks. Every single dot in the sky is another star, galaxy, planet, asteroid, etc. They are not blemishes in the image. To just write them off would be like drawing a map of the earth without New Zealand on it.

Balgair 6y ago
To reinforce this, there is a fair bit of astronomy that is looking for single photon differences. The optics and engineering here is very cool (pun intended) and can take months of time on an instrument to detect, if there is anything at all. Sources of noise are pathologically chased down. Adding in noise would be like trying to chop off your arm, easy to do once, but hard to undo. As a reminder, astronomy is not as much about the 'image' as it is about the 'measurement'. Editing pictures like in Insta is not the point here, you can't fill things in.
- dylan604 6y ago
  Exactly. Modern day comet/asteroid hunters are taking images from night after night and treating them like time lapses to see what dots are moving. Removing these dots to fill in the void left by the satellite streaks sets this method of detection back to unusable/unreliable. Even filling in the removed satellite streaks in an image with data from previous/next images totally invalidates the tracking of objects in motion.
verytrivial 6y ago
.. and I have given up chasing down the 'JuSt UsE SpaCE teLeScoPEs' comments. These people would write off the loss of New Zealand as the market simply finding the right benefit-cost ratio.

crazygringo 6y ago

No, that's not how that works at all. Remember, astronomy images generally have long exposure times, which already involve tracking the sky, and then averaging out values in the exposure across minutes/hours/days/whatever. A satellite passing over a point in the sky means that area of sky is affected for only a tiny fraction of the total exposure. As long as you have a database of all satellite locations, you just don't include data from those time slices in the final average. Or if you don't know where satellites are in advance, you just do basic outlier detection -- the kind that already eliminates things like airplanes, birds, the ISS, etc. Nobody's filling in anything with "black", and the area of satellite interference can be easily expanded to include the "glow" area. In the end, the quality of the overall image is degraded by a tiny fraction of a percentage, which can be trivially overcome by extending the total exposure time by the same tiny fraction of a percentage.