6 ms·

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. Get

by 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.
    - 0-_-0 6y ago
      2% is trivial. They lost 2% of information (as someone pointed out this might be closer to 20%). This means the cost to the astronomer was 2% (or 20%). Calling this "ruining" is an exaggeration. Of course it would ruin a pretty picture, but "This isn't about people taking pretty pictures, this is about people trying to do actual work." where you can choose the part of information you take into account.
      - Balgair 6y ago
        Except if the thing you're trying to measure is in that 20%. Astronomy is time limited, you may never get the opportunity again.
- valuearb 6y ago
  If the entire field of astronomy is so educated on the subject, why do most not know Starlink was never visible except at dawn or dusk, and it’s already implemented successful mitigations for those tones with visors?
  - dayjobpork 6y ago
    Unless Musk has secretly invented Romulan cloaking technology, being invisible doesn't help when you are trying to look at the stuff behind
    - valuearb 6y ago
      What percentage of the night sky will be obscured if Starlink goes to 30,000 satellites? Let me guess, if the visual radius of a one meter satellite 550,000 meters away is (1/X)^2. Thirty thousand would be 1/one trillion, or far less?
      - huonpine 6y ago
        Its not just about Starlink though, its about setting a precedent before every company and country starts launching competing constellations. When should we start to care after the first few thousand or after hundred of thousands of eventual satellite's?
        valuearb 6y ago
        It would take trillions to appreciably dim the night sky. Wake me then.
  - astrophysician 6y ago
    ...wow. (1) astronomers are pretty darn aware of everything going on, and it's really shocking as an astronomer to see these sorts of claims. There have been close collaborations with Space X to try to mitigate some issues, but these are partial mitigations and the most important ones are only planned, not implemented. The "successful" mitigations I think you're referring to is their "DarkSat" coating, which is not actually a successful mitigation. It is still ~2x as bright as the ~maximum level of acceptable brightness for e.g. LSST. (2) Space-X did not release any details about brightness characteristics, and they themselves claim that they were "surprised" by the brightness. To people that work in space rather routinely, that is staggeringly incompetent. (3) > why do most not know Starlink was never visible except at dawn or dusk Near earth object (NEO) detection only happens during these times. NEO includes "asteroids that threaten human life" so I would hope you agree that this is pretty important. Also, depending on latitude and time of year, "dawn or dusk" can constitute your entire observing window. So this doesn't really make things better. (4) all of these mitigations should be done before companies can start doing ~10,000 satellite launches. The only reason this isn't done is outdated legislation that never conceived of this being possible.
welterde 6y ago
CCDs are not really receivers that can be turned off for a couple seconds. A physical shutter moves in front of the detector and covers it (for most instruments as they exist right now).
- 0-_-0 6y ago
  Can you move the shutter in front of the receiver when you know a satellite will transit?
  - welterde 6y ago
    Sure. And for small field of view things that might be the future. But if you are looking at large chunks of the sky at some point with enough satellites the shutter will have to stay shut for the whole duration of the exposure.. so not really a good solution for that.
    - 0-_-0 6y ago
      (can't reply below) If you had a localised shutter covering pattern X for 6 seconds, could you compensate for that by covering the inverse pattern of X for 6 seconds to get the same exposure for all pixels? So if you covered 3 satellite streaks of 6 seconds each using non-verlapping patterns (A,B,C) you could compensate for that by ending your exposure with covering the inverse of A+B+C for 6 seconds, adding only 6 seconds to your total exposure time and get uniform exposure.
      - welterde 6y ago
        If the conditions are quite stable that might work (or if one can live with limited accuracy), but conditions tend to change over time (moon position, thin clouds and of course the seeing - how much the atmosphere distorts the image) so nothing is as straightforward as one might hope for. In space that approach would work quite well indeed, but then you wouldn't need it in the first place.. Edit: Even if one still has to mask the streak in the data in the end, it might still be useful to do, since it will protect the rest of the image from any excess blooming.
51Cards 6y ago
In this sample image it's not just the white streak but the glow caused by it which extends about 5-8x it's width to either side. More like 20% of this image is unreliable data. Taking multiple exposures isn't always possible, this may be a continuous multi-hour exposure. Additionally if you're looking for transients, NEOs, or star field mapping then there is definitely lost data that can't just be inferred. The conversation isn't just about halting launches. It's about recognizing and working to mitigate the issue now before we get too far down this path.... and accepting that it's not a trivial "photoshop" problem.
dylan604 6y ago
1-2% of the size of the entire Universe is trivial to you?

by 0-_-0 6y ago

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.
  - 0-_-0 6y ago
    2% is trivial. They lost 2% of information (as someone pointed out this might be closer to 20%). This means the cost to the astronomer was 2% (or 20%). Calling this "ruining" is an exaggeration. Of course it would ruin a pretty picture, but "This isn't about people taking pretty pictures, this is about people trying to do actual work." where you can choose the part of information you take into account.
    - Balgair 6y ago
      Except if the thing you're trying to measure is in that 20%. Astronomy is time limited, you may never get the opportunity again.
valuearb 6y ago
If the entire field of astronomy is so educated on the subject, why do most not know Starlink was never visible except at dawn or dusk, and it’s already implemented successful mitigations for those tones with visors?
- dayjobpork 6y ago
  Unless Musk has secretly invented Romulan cloaking technology, being invisible doesn't help when you are trying to look at the stuff behind
  - valuearb 6y ago
    What percentage of the night sky will be obscured if Starlink goes to 30,000 satellites? Let me guess, if the visual radius of a one meter satellite 550,000 meters away is (1/X)^2. Thirty thousand would be 1/one trillion, or far less?
    - huonpine 6y ago
      Its not just about Starlink though, its about setting a precedent before every company and country starts launching competing constellations. When should we start to care after the first few thousand or after hundred of thousands of eventual satellite's?
      - valuearb 6y ago
        It would take trillions to appreciably dim the night sky. Wake me then.
- astrophysician 6y ago
  ...wow. (1) astronomers are pretty darn aware of everything going on, and it's really shocking as an astronomer to see these sorts of claims. There have been close collaborations with Space X to try to mitigate some issues, but these are partial mitigations and the most important ones are only planned, not implemented. The "successful" mitigations I think you're referring to is their "DarkSat" coating, which is not actually a successful mitigation. It is still ~2x as bright as the ~maximum level of acceptable brightness for e.g. LSST. (2) Space-X did not release any details about brightness characteristics, and they themselves claim that they were "surprised" by the brightness. To people that work in space rather routinely, that is staggeringly incompetent. (3) > why do most not know Starlink was never visible except at dawn or dusk Near earth object (NEO) detection only happens during these times. NEO includes "asteroids that threaten human life" so I would hope you agree that this is pretty important. Also, depending on latitude and time of year, "dawn or dusk" can constitute your entire observing window. So this doesn't really make things better. (4) all of these mitigations should be done before companies can start doing ~10,000 satellite launches. The only reason this isn't done is outdated legislation that never conceived of this being possible.

welterde 6y ago

CCDs are not really receivers that can be turned off for a couple seconds. A physical shutter moves in front of the detector and covers it (for most instruments as they exist right now).

0-_-0 6y ago
Can you move the shutter in front of the receiver when you know a satellite will transit?
- welterde 6y ago
  Sure. And for small field of view things that might be the future. But if you are looking at large chunks of the sky at some point with enough satellites the shutter will have to stay shut for the whole duration of the exposure.. so not really a good solution for that.
  - 0-_-0 6y ago
    (can't reply below) If you had a localised shutter covering pattern X for 6 seconds, could you compensate for that by covering the inverse pattern of X for 6 seconds to get the same exposure for all pixels? So if you covered 3 satellite streaks of 6 seconds each using non-verlapping patterns (A,B,C) you could compensate for that by ending your exposure with covering the inverse of A+B+C for 6 seconds, adding only 6 seconds to your total exposure time and get uniform exposure.
    - welterde 6y ago
      If the conditions are quite stable that might work (or if one can live with limited accuracy), but conditions tend to change over time (moon position, thin clouds and of course the seeing - how much the atmosphere distorts the image) so nothing is as straightforward as one might hope for. In space that approach would work quite well indeed, but then you wouldn't need it in the first place.. Edit: Even if one still has to mask the streak in the data in the end, it might still be useful to do, since it will protect the rest of the image from any excess blooming.

51Cards 6y ago

In this sample image it's not just the white streak but the glow caused by it which extends about 5-8x it's width to either side. More like 20% of this image is unreliable data. Taking multiple exposures isn't always possible, this may be a continuous multi-hour exposure. Additionally if you're looking for transients, NEOs, or star field mapping then there is definitely lost data that can't just be inferred. The conversation isn't just about halting launches. It's about recognizing and working to mitigate the issue now before we get too far down this path.... and accepting that it's not a trivial "photoshop" problem.

dylan604 6y ago

1-2% of the size of the entire Universe is trivial to you?