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Is STARLINK going to impact astrophotography?

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#26 Francois

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Posted 28 May 2019 - 04:29 PM

No some of the Northern States will suffer also.

 

Steve

Those never leave formal twilight in the summer. So it's always dusk or dawn, north/southwards. For reference, all sites at less than 45 degrees absolute latitude will have a midnight zenith free of Starlink at the solstice. Basically the sun illumination constraint draws a bright Starlink-free zone in the sky opposite to the sun.

 

If you really want to be scared, OneWeb's sats are illuminated all the way to 33 degrees past the terminator. That is much, much worse. Those will actually interfere with professional observatories.


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#27 Jon Rista

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Posted 28 May 2019 - 04:40 PM

Those never leave formal twilight in the summer. So it's always dusk or dawn, north/southwards. For reference, all sites at less than 45 degrees absolute latitude will have a midnight zenith free of Starlink at the solstice. Basically the sun illumination constraint draws a bright Starlink-free zone in the sky opposite to the sun.

 

If you really want to be scared, OneWeb's sats are illuminated all the way to 33 degrees past the terminator. That is much, much worse. Those will actually interfere with professional observatories.

There are other ways to get internet to the remote corners of the world...one not so destructive to astronomy. It's too bad no one really thought all of this through or put the break on it a bit, so that the real consequences of tossing so many satellites into orbit could really be considered in depth...



#28 goodricke1

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Posted 28 May 2019 - 04:52 PM

There are other ways to get internet to the remote corners of the world...one not so destructive to astronomy. It's too bad no one really thought all of this through or put the break on it a bit, so that the real consequences of tossing so many satellites into orbit could really be considered in depth...

 

Yes it's amazing how quickly this has unfolded and that no debate seems to have taken place about the detrimental aspects. Musk himself was on Twitter acknowledging the concerns but not sounding overly apologetic; talking about 'the greater good'. It seems like Wild West laws apply in near-Earth orbit.



#29 Francois

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Posted 28 May 2019 - 04:52 PM

There are other ways to get internet to the remote corners of the world...one not so destructive to astronomy. It's too bad no one really thought all of this through or put the break on it a bit, so that the real consequences of tossing so many satellites into orbit could really be considered in depth...

It's been in consideration for 3 or 4 years depending on the constellation, and very publicly discussed. This is not some kind of Douglas Adamsian scheme where the approval was given in the dead of night. Third party motions could even be made electronically. The apparent magnitude of a square meter of reflective material in orbit is not some dark magic either.



#30 t-ara-fan

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Posted 28 May 2019 - 05:02 PM

It's been in consideration for 3 or 4 years depending on the constellation, and very publicly discussed. 

Allow me to quote The Hitchhikers Guide to the Galaxy:

 

"But the plans were on display . . ."
"On display? I eventually had to go down to the cellar to find them."
"That's the display department."
"With a torch."
"Ah, well the lights had probably gone."
"So had the stairs."
"But look, you found the notice, didn't you?"
"Yes," said Arthur, "yes I did. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying Beware of the Leopard."


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#31 Francois

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Posted 28 May 2019 - 05:13 PM

Allow me to quote The Hitchhikers Guide to the Galaxy:

 

"But the plans were on display . . ."
"On display? I eventually had to go down to the cellar to find them."
"That's the display department."
"With a torch."
"Ah, well the lights had probably gone."
"So had the stairs."
"But look, you found the notice, didn't you?"
"Yes," said Arthur, "yes I did. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying Beware of the Leopard."

But in this case, they were on the internet, widely discussed in IT and space media, and there's no tiger in Africa.



#32 freestar8n

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Posted 28 May 2019 - 05:40 PM

If you have a stack of images, then each stack at a given pixel will likely have at most one satellite trail.  The only time a pixel would have two is when two trails intersect.  And that could well happen - but it is rare and would still only amount to the need to reject two exposures in the stack.  In order for a pixel to have 3 satellite trails - you would need three trails intersecting at exactly the same point - which would be extremely unlikely.  So even if the number of satellites increases a fair amount - the core rejection task isn't much different from the way it is currently.

 

The trails do have finite width in the image - and two could be very close and parallel - allowing a third that crosses to result in 3 hot pixels in a stack.  But that is still rare - and would reject easily with a decent number of frames.

 

As for the LSST - it is already set up to reject satellite trails - and they take two successive exposures at each target.  This will mean more clean up of the exposures - but again I don't think the increased number of trails will have much impact.  I haven't seen concerns by the LSST astronomers themselves about StarLink - but I do see web discussions alluding to the impact on LSST.

 

As bad as this all is - I don't currently see a big problem for imaging or the LSST.

 

Frank


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#33 Jon Rista

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Posted 28 May 2019 - 06:11 PM

It isn't just StarLink...it is the trend being put into place with StarLink. This push to put tens of thousands of new satellites into space for...whatever reason, because you can. When you go from 4900 to 17,000, to 25,000, to 50,000, to 100,000 satellites or more...then you have a compounding problem if something goes wrong with one if them. What happens WHEN one of them fails to respond to a command (we have already had two countries purposely destroy one of their satellites, resulting in tens of thousands to hundreds of thousands of pieces of debris in orbit...with tens of thousands of additional satellites, I think it is more of an inevitability than a possibility, especially with mass-produced satellites thrown up there on any whim), or responds improperly, and flies into another satellite, destroying both...then leaving you with Kessler syndrome. You could wipe out an entire orbit. What do you do then with the billions of pieces of useless, uncontrolled junk littering the entire sky...how does that affect astronomy (not just astrophotography but astronomy in general)? What kind of monumental and costly cleanup effort would it take to actually restore the orbit to usability again? Would it even be possible to restore an orbit affected by Kessler syndrome?

 

I honestly don't know that all the angles have been considered here in the depth they should have been considered. I really don't see a catastrophe that could obliterate an entire orbital band as a remote possibility here...the more satellites we put up there, the greater the chance something will go wrong, and the more satellites that are up there, the more likely when something goes wrong that it will be a devastating cascade...


Edited by Jon Rista, 28 May 2019 - 10:49 PM.

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#34 chadrian84

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Posted 29 May 2019 - 12:18 AM

Musk on twitter: “We need to move telelscopes to orbit anyway. Atmospheric attenuation is terrible.”... Doesn’t sound like someone who’s concerned about amateur astronomy.

I’m uninformed but concerned. When several thousand of these are in orbit it will be impossible to put Humpty- Dumpty back together.
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#35 Tapio

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Posted 29 May 2019 - 12:21 AM

Maybe Musk can provide cheap amateur telescopes in orbit ?


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#36 vdb

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Posted 29 May 2019 - 12:49 AM

Musk on twitter: “We need to move telelscopes to orbit anyway. Atmospheric attenuation is terrible.”... Doesn’t sound like someone who’s concerned about amateur astronomy.

I’m uninformed but concerned. When several thousand of these are in orbit it will be impossible to put Humpty- Dumpty back together.

if he dedicates 2% of the starlink cargo to amateurs ... we should start developing mini sat's:-D

 

/Yves



#37 Francois

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Posted 29 May 2019 - 02:51 AM

Musk on twitter: “We need to move telelscopes to orbit anyway. Atmospheric attenuation is terrible.”... Doesn’t sound like someone who’s concerned about amateur astronomy.

I’m uninformed but concerned. When several thousand of these are in orbit it will be impossible to put Humpty- Dumpty back together.

If you had not noticed yet, Musk is a huge bloviating rectum. I submit the "pedo guy", and FTC incidents as proof.

 

In any case, it's already too late to stop initial deployment of either Starlink or OneWeb since they already have regulatory approval, and have actually started (way back in February for OneWeb). Go lookup "ONEWEB-*" at heavens-above for your location. They're fairly bright and for anyone at >35 degrees latitude they go all the way to zenith at midnight this time of year.



#38 vdb

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Posted 30 May 2019 - 02:03 AM

If you still doubt that it will not interfere;

 

Screenshot 2019-05-30 at 09.01.30.jpg


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#39 freestar8n

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Posted 30 May 2019 - 04:36 AM

If you still doubt that it will not interfere;

 

attachicon.gif Screenshot 2019-05-30 at 09.01.30.jpg

Yes - I still doubt that will interfere *with deep sky imaging*.  None of the trails actually cross - so in a stack of images there will be only one frame to reject for each pixel stack.  I see some blurred trails that overlap - and that will mean maybe two frames to reject.  That isn't a lot different from how things work now.  And for LSST - there will be trails in one exposure and trails in the next.  Looking at both they should be able to remove the trails and get the underlying data.

 

I'm not saying this stuff is ok.  I'm just saying that imaging and scientific work are already set up to deal with this stuff.  The much higher volume of trails does not pose a fundamental problem by itself.

 

Frank


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#40 freestar8n

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Posted 30 May 2019 - 04:49 AM

Musk on twitter: “We need to move telelscopes to orbit anyway. Atmospheric attenuation is terrible.”... Doesn’t sound like someone who’s concerned about amateur astronomy.

I’m uninformed but concerned. When several thousand of these are in orbit it will be impossible to put Humpty- Dumpty back together.

I checked and he does appear to have used the term, "Atmospheric attenuation" - and that is not the right term to use here.  Attenuation is not a big deal - but atmospheric turbulence and light pollution are fundamental issues for terrestrial work.  It's a telling error that conveys he is out of his comfort zone on this issue - as his satellite parade leaves ominous trails across the sky.

 

Frank


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#41 vdb

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Posted 30 May 2019 - 04:56 AM

Yes - I still doubt that will interfere *with deep sky imaging*.  None of the trails actually cross - so in a stack of images there will be only one frame to reject for each pixel stack.  I see some blurred trails that overlap - and that will mean maybe two frames to reject.  That isn't a lot different from how things work now.  And for LSST - there will be trails in one exposure and trails in the next.  Looking at both they should be able to remove the trails and get the underlying data.

 

I'm not saying this stuff is ok.  I'm just saying that imaging and scientific work are already set up to deal with this stuff.  The much higher volume of trails does not pose a fundamental problem by itself.

 

Frank

Maybe for pretty pictures it's not that big of an issue, but even in that case you will have more noise and in really low SNR objects I can even detect the impact of one trail, because I know where it is ... But for scientific I'm not sure ... I can imagine they don't want to waste to much time on an object to measure something ... 



#42 freestar8n

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Posted 30 May 2019 - 05:03 AM

Maybe for pretty pictures it's not that big of an issue, but even in that case you will have more noise and in really low SNR objects I can even detect the impact of one trail, because I know where it is ... But for scientific I'm not sure ... I can imagine they don't want to waste to much time on an object to measure something ... 

Both pretty pictures and Hubble/Science involve multiple exposures and some form of rejection of outliers.  As long as you have more than one image you have a lot to go by - in terms of rejecting cosmic rays, satellites - all kinds of things that are dealt with already.

 

For LSST they are explicitly dealing with two exposures at a time right after each other.  Each about 15s long.  There would be many more trails in each exposure with Starlink in the sky - but with two exposures you have a lot of info on how to identify trails in each exposure and ignore only that data - and use everything else.

 

And that's an issue that already exists even without Starlink.

 

Frank


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#43 David_Ritter

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Posted 30 May 2019 - 05:54 AM

When there are tens of thousand, or even millions of these things up there, it's a pretty safe bet that almost every single frame I take will be littered with trails. So as far as I'm concerned, these things will ruin astro-photography for me. I have no interest in sifting through millions of garbage pixels looking for the few good ones left.


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#44 freestar8n

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Posted 30 May 2019 - 06:04 AM

When there are tens of thousand, or even millions of these things up there, it's a pretty safe bet that almost every single frame I take will be littered with trails. So as far as I'm concerned, these things will ruin astro-photography for me. I have no interest in sifting through millions of garbage pixels looking for the few good ones left.

If every frame has satellite trails - that is no different from today - with cosmic rays and other things impacting every single frame.

 

When you have 2 or more frames - all that matters is if those events correlate in the stack.  And aside from parallel, overlapping trails - which I think is unlikely once these things are positioned properly - I expect even 2 frames will allow good rejection of pixels affected by satellite trails.  Hence little impact on SNR or anything else.

 

I think it's important to separate the consequences of this stuff on imaging and scientific work - which I think are minimal - from the aesthetic experience of a dark night sky.  The latter will be severely impacted - while the former won't.  I don't think it's good to conflate the two - since the latter is important by itself.  But the latter is in the same category as light pollution - and somewhat a lost cause already, I'm afraid.

 

Frank


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#45 t_image

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Posted 30 May 2019 - 06:52 AM

I think it's important to separate the consequences of this stuff on imaging and scientific work - which I think are minimal - from the aesthetic experience of a dark night sky.

Distinctions are very important, well said.

However even now it's not really hard to capture satellites with what one may expect is not a "likely occurrence":

(for ex. video of a trio of satellites crossing the path of a pair of satellites)

https://www.youtube....h?v=wGWcGlCeeKQ

The "perfect storm" of unhelpful confluences of a key image acquired while a pass/flare occurs will ___-fold increase when you up the number of LEO satellites by the scale these mega-constellation anticipate...

 

Processing stacks of long exposures for a pretty picture is different that some other astronomic imaging methods:

time lapses

meteor shower images

occultations,

exoplanet candidate measurements,

etc.

PixInsight scripts won't immediately solve the issues of processes where momentary captures that don't have luxury of stacks is needed....

and this will not only be an issue for optical imaging, but for other spectrum types (like radio astronomy) as well....

Not saying that we can determine the degree of impact yet and there are usually work-arounds,

but what happens when the one-time glint off a potentially hazardous asteroid is approaching the Earth and at that very moment a satellite passes through the view and hides the asteroid's optical signature and it so happens to be in a position that it otherwise hides from detection until it's too late............

 

So there is also a distinction between normal day-to-day operations, compared with the increase of "perfect storm" occurrences that then might ruin important data collection....



#46 freestar8n

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Posted 30 May 2019 - 07:07 AM

Distinctions are very important, well said.

However even now it's not really hard to capture satellites with what one may expect is not a "likely occurrence":

(for ex. video of a trio of satellites crossing the path of a pair of satellites)

https://www.youtube....h?v=wGWcGlCeeKQ

The "perfect storm" of unhelpful confluences of a key image acquired while a pass/flare occurs will ___-fold increase when you up the number of LEO satellites by the scale these mega-constellation anticipate...

 

Processing stacks of long exposures for a pretty picture is different that some other astronomic imaging methods:

time lapses

meteor shower images

occultations,

exoplanet candidate measurements,

etc.

PixInsight scripts won't immediately solve the issues of processes where momentary captures that don't have luxury of stacks is needed....

and this will not only be an issue for optical imaging, but for other spectrum types (like radio astronomy) as well....

Not saying that we can determine the degree of impact yet and there are usually work-arounds,

but what happens when the one-time glint off a potentially hazardous asteroid is approaching the Earth and at that very moment a satellite passes through the view and hides the asteroid's optical signature and it so happens to be in a position that it otherwise hides from detection until it's too late............

 

So there is also a distinction between normal day-to-day operations, compared with the increase of "perfect storm" occurrences that then might ruin important data collection....

There was a recent important Nature publication of a small Kuiper-belt asteroid causing a very brief occultation.  Even before Starlink they had to rule out a possible blink caused by a satellite - so they used two separated telescopes and calculated the odds of a false positive.

 

I don't think the odds are significantly impacted by Starlink in that case.  And that was a very unusual case of a realtime occultation study from Earth.  Most scientific work is not realtime like that - and can figure out even from two longish exposures - what pixels to reject.

 

If you are concerned about coincidences of one time glints with other things - that can already happen with multiple cosmic rays in exposures.  They always have to calculate false positives based on models of what might happen.  Even with all these new satellites - I don't see the odds of very rare coincidences increasing significantly.

 

Frank

 

addendum - With regard to your trio of satellites - no problem at all.  The concern is if 3 trails cross over the same exact pixel in 3 exposures.  And even then - if you have a large number of exposures it will still be rejected.  Your video just shows multiple satellites doing different things.  There would be no correlation in a stack.  It doesn't matter if they "cross the trail."  The concern is if all cross over the exact same pixel - to produce three hot pixels in a stack.  And that will be rare - and even then it is ignorable if you have a number of frames.

 

Frank


Edited by freestar8n, 30 May 2019 - 07:19 AM.

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#47 spokeshave

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Posted 30 May 2019 - 08:38 AM

I'm inclined to agree with Frank. the impact to amateur astrophotography will be minimal. I recently completed an image of NGC2170 and each sub has a train of NOSS satellites through it. Each sub was a mess, but with proper rejection technique, there were no traces in the final image and virtually zero SNR loss. I've never understood why people reject subs with trails in them. 99.XX% of the pixels in those subs are unimpacted and proper rejection will fix the remaining 0.YY% The ever-increasing encroachment of light pollution has a much, much greater impact on this hobby.

 

On the other hand, the impact to the dark sky aesthetic is probably going to be greater. It is probably going to get increasingly more difficult to get lost in the majesty of the visible universe when every portion of the sky has some obvious artificial satellite in it. But then, it is a bit Quixotic to complain about it, so I won't. Technological and societal progress is a windmill that will resist all tilting. 

 

Tim


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#48 funkysandman

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Posted 30 May 2019 - 09:40 AM

Aside from the annoyance of the ruined subs, I thought there was another phenomena of making space travel extremely dangerous due to the amount of material in these shells around earth?

 

https://youtu.be/yS1ibDImAYU


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#49 Jon Rista

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Posted 30 May 2019 - 11:06 AM

Both pretty pictures and Hubble/Science involve multiple exposures and some form of rejection of outliers.  As long as you have more than one image you have a lot to go by - in terms of rejecting cosmic rays, satellites - all kinds of things that are dealt with already.

 

For LSST they are explicitly dealing with two exposures at a time right after each other.  Each about 15s long.  There would be many more trails in each exposure with Starlink in the sky - but with two exposures you have a lot of info on how to identify trails in each exposure and ignore only that data - and use everything else.

 

And that's an issue that already exists even without Starlink.

 

Frank

You really need more than just two images. You need to be able to robustly locate a mean in order to reject outliers. And to call the image vdb shared a non-issue, consider when there are not just 60, but 12,000 of these things up there, on top of the thousands from OneWeb, and eventually thousands to tens of thousands more other satellite swarms on top of that. You honestly do not think that multiple frames will be criss-crossed with bright satellite trails all the time, often overlapping at various locations in the frame? 



#50 555aaa

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Posted 30 May 2019 - 12:22 PM

I don't think it is looking very good for wide field nature-type imaging. You're going to go outside and try to get those nice milky way images and now you are saying that all the nature photographers need pixinsite and to start stacking images?

 

How are we going to teach kids about the constellations when you can't see them anymore because every where you are looking at a star you are also seeing a satellite? It could get really bad. 


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