Impacts of Large Satellite Constellations on Astronomy

[ncb1397]

After looking at the data more, I was curious about the hits in June. For instance, 6/3/2020 23:52:00 UTC has a 42 degree spacecraft elevation but a sun angle of -26 degrees. Just to validate the methodology, I put the spacecraft in the viewport on the limb of the earth with the sun in the background and it does indeed look like it would be lit (so GMAT is calculating shadowing correctly). NOAA's solar calculator indicates sunrise would be 21:49 meaning this would be over two hours after sunset and so the solar angle looks plausible. And then looking at the ground plot and the longitude/latitude differences(almost identical latitude, longitude a few degrees off), the ~45 degree elevation angle looks about right as well. See simulation paused on this event in the linked screenshot.

Beyond that, I uploaded the output for 72 orbital planes, 22 satellites per plane at the same time and ground station location from https://www.howmanystarlinkswillfillyoursky.com/. It appears to get results of up to about 35-40 degrees elevation(eye balling) which is consistent with my result of a 42 degree occurrence(any disparity could be due to the exact details of how the satellites are initialized).

[ncb1397]

Astronomical twilight occurs when the Sun is between 12 degrees and 18 degrees below the horizon.

https://www.timeanddate.com/astronomy/different-types-twilight.html#:~:text=Astronomical%20twilight%20occurs%20when%20the,the%20sky%20is%20absolutely%20dark.

The examples above were all <-18 degree solar elevation so past astronomical twilight (and the data is provided so you can filter it yourself). And the chart you are referencing isn't the be all end all. For one, it is practically unreadable(too low res?). For two, it lumps everything >20 elevation together. Maybe 21 degrees is slightly different than 50 or 60? Either way, the description that I responded to about starlink that people had an issue with because of only one data point has been fleshed out. There are clearly lit transits not on the horizon for satellites at 550 km (and they aren't rare). Your graph doesn't help me there because the argument could be made that >20 means 20-25 degrees or something and "on the horizon". Beyond that, people were saying that the time of year was cherry picked, but similar events happen in June as farther simulation into the year shows.

[eeergo]

To add to the all-wavelength visibility issues mostly discussed so far (for which there are increasingly detailed assessments on exactly how much megaconstellations would impact different other fields - it clearly ranges from "annoying but manageable" in the most favorable cases with some IOC constellations, to very problematic or even catastrophic for full megaconstellations or at high altitude), some hard data is also starting to trickle in about in-space impacts such as space debris, tied to reliability and foreseeable unexpected failure rate, or impacts to LEO space telescopes like HST, as posted upthread.

https://twitter.com/JareelSkaj/status/1280980444801105929

[niwax]

Jonathan McDowell, among others, has pages of high-quality analysis under https://planet4589.org/astro/starsim/index.html
. He includes detailed simulations at different latitudes and times of year: https://planet4589.org/astro/starsim/vis.html.

OneWeb even in its smallest incarnation is vastly more damaging than a fully deployed Starlink. Note the 10x larger Y-axis. Kuiper is so-so. In general I would be in favor of strongly limiting satellite deployments over 550-600km, both for astronomy and debris concerns, as well as a set of best practices in regards to darkening and reflection-avoiding operations.

[ncb1397]

OneWeb even in its smallest incarnation is vastly more damaging than a fully deployed Starlink.

Your linked photos don't show that. OW2 in photo #3 refers to ~48,000 satellites (which is a very different story than the ~600 "smallest configuration"). His definitions for terminology is here...

https://planet4589.org/astro/starsim/con.html

For whatever reason, of all charts generated, none of them show OW1 (or what I assume he would call One Web Gen 1...the Soyuz contract). I agree that the oneweb gen 2 constellation is a bad design, but it isn't really clear that they actually want to deploy all those satellites at those altitudes and at mixed inclinations to boot. They just want flexibility and once they get approval, it would be easier to change inclination/orbital planes/elevation as Starlink has demonstrated (Or at least that could be an explanation of what is occuring). The FCC application makes it clear that this is a maximum number as well. And it should also be pointed out that none of your uploaded models show starlinks above ~1000 km, which they currently have approval for ~3000 such satellites and as far as I know the orbit lowering hasn't been approved. In that regard, OW2 and Starlink are similar.

Maybe somebody should ask HMG about what their intentions are.

[envy887]

OneWeb even in its smallest incarnation is vastly more damaging than a fully deployed Starlink.

Your linked photos don't show that. OW2 in photo #3 refers to ~48,000 satellites (which is a very different story than the ~600 "smallest configuration"). His definitions for terminology is here...

https://planet4589.org/astro/starsim/con.html

For whatever reason, of all charts generated, none of them show OW1 (or what I assume he would call One Web Gen 1...the Soyuz contract). I agree that the oneweb gen 2 constellation is a bad design, but it isn't really clear that they actually want to deploy all those satellites at those altitudes and at mixed inclinations to boot. They just want flexibility and once they get approval, it would be easier to change inclination/orbital planes/elevation as Starlink has demonstrated (Or at least that could be an explanation of what is occuring). The FCC application makes it clear that this is a maximum number as well. And it should also be pointed out that none of your uploaded models show starlinks above ~1000 km, which they currently have approval for ~3000 such satellites and as far as I know the orbit lowering hasn't been approved. In that regard, OW2 and Starlink are similar.

Maybe somebody should ask HMG about what their intentions are.

2,800 satellites is similar to 48,000 satellites?

SpaceX has never sent a single Starlink to 1000+ km, has indicated no plans to do so after the initial approval several years ago, has requested modifications lowering the orbits for all the Gen 1 constellation, and submitted the request for Gen 2 at the lower orbits. Every indication is that they intend to ONLY operate below 650 km.

OneWeb is operating satellites at 1000+ km, has consistently stated plans to deploy the remainder of the first gen constellation there, and requested that their second gen constellation deploy there. Every indication is that they intend to ONLY operate above 1000 km.

How are those even slightly similar?

[NaN]

I agree that the oneweb gen 2 constellation is a bad design, but it isn't really clear that they actually want to deploy all those satellites at those altitudes and at mixed inclinations to boot. They just want flexibility and once they get approval, it would be easier to change inclination/orbital planes/elevation as Starlink has demonstrated (Or at least that could be an explanation of what is occuring). [...]

Maybe somebody should ask HMG about what their intentions are.

We have to assume that the license request indicates the actual plan as once it's approved, they are free to deploy as licensed AFAIK. Notably, the Starlink modification requests that you mentioned have either improved or left unchanged the orbital debris potential and constellation visibility, by reducing or leaving unchanged sat count and altitude (and moving planes around). By contrast the OneWeb modification request would make things substantially (70 times??) worse.

[ncb1397]

I agree that the oneweb gen 2 constellation is a bad design, but it isn't really clear that they actually want to deploy all those satellites at those altitudes and at mixed inclinations to boot. They just want flexibility and once they get approval, it would be easier to change inclination/orbital planes/elevation as Starlink has demonstrated (Or at least that could be an explanation of what is occuring). [...]

Maybe somebody should ask HMG about what their intentions are.

We have to assume that the license request indicates the actual plan as once it's approved, they are free to deploy as licensed AFAIK. Notably, the Starlink modification requests that you mentioned have either improved or left unchanged the orbital debris potential and constellation visibility, by reducing or leaving unchanged sat count and altitude (and moving planes around). By contrast the OneWeb modification request would make things substantially (70 times??) worse.

We should probably differentiate between stuff that is requested and approved and stuff that is requested and not approved and no where close to deployment (no hardware build, no launches bought and scheduled, etc.). As has been pointed out, Starlinks request and approval for thousands of 1000 km+ satellites doesn't actually, in fact, matter (assuming the request to lower is approved and doesn't have radio frequency/interference/spectrum effects that preclude). Below is a quick comparison between satellite charts for one web and spacex for two points in time from the previously mentioned ground station. Starlink is 72 orbital planes with 22 satellites each at 53 degree inclination and 550 km altitude. One Web is 18 orbital planes of 36 satellites each at 87.9 degree inclination at 1200 km. Note that the movement of satellites within orbital planes is much faster than the speed of the orbital planes through the sky. From my eye, they appear to interfere with a similar amount of the sky (in both cases, more starlinks are visible and are higher magnitude as well). Based on comments from astronomers, they didn't necessarily care that much about 8th magnitude + objects either. They cared about stuff that would cause secondary affects to their observations as a whole and not just a set of pixels.

image source with permission: www.howmanystarlinkswillfillyoursky.com

[NaN]

We should probably differentiate between stuff that is requested and approved and stuff that is requested and not approved and no where close to deployment (no hardware build, no launches bought and scheduled, etc.).

We should differentiate, yes - but my point was that astronomers can't optimistically assume that requests will be denied and that approved licenses will not be utilized. The earlier they raise legitimate objections, the better it is for everyone. Modelling the full plans/requests is the way to do this.

[...] Based on comments from astronomers, they didn't necessarily care that much about 8th magnitude + objects either. They cared about stuff that would cause secondary affects to their observations as a whole and not just a set of pixels.

The secondary effects from sensor saturation are the most critical thing that I've heard of (because they can wipe out swaths of pixels), but in general the brightness per pixel (function of brightness and transit rate) coupled with the visible satellite count is also extremely important for determining how well the observations can be corrected or can proactively avoid passes. And it can be a significant impact particularly for LSST. It varies by observation type and is hard to collapse to a simple function. If you're interested then I highly recommend this paper: https://arxiv.org/pdf/2003.01992.pdf

[meberbs]

Below is a quick comparison between satellite charts for one web and spacex for two points in time from the previously mentioned ground station. Starlink is 72 orbital planes with 22 satellites each at 53 degree inclination and 550 km altitude. One Web is 18 orbital planes of 36 satellites each at 87.9 degree inclination at 1200 km. Note that the movement of satellites within orbital planes is much faster than the speed of the orbital planes through the sky. From my eye, they appear to interfere with a similar amount of the sky (in both cases, more starlinks are visible and are higher magnitude as well).

You are picking just a couple specific points in time, but this completely fails to illustrate the fact shown in multiple plots above that the higher altitude satellites are visible throughout the entire night (except maybe a small period for the smallest OneWeb shell in Jonathan Mcdowell's plot, hard to say due to the scale) While the Starlink illuminated satellites above low elevation (using an angle chosen by someone who is an astronomer) drops to zero for the majority of the night (defined by astronomical twilight.) This has been shown with more complete analysis than anything you have done, and from multiple sources.

[thirtyone]

Some of the comments here are based on outdated understanding of these constellations. Most of the answers are upthread already. There is a lot of peer reviewed literature by professional astronomers from the AAS who are both focused on this problem, working with SpaceX, and have looked at orbital debris/satellites for their entire careers. It would be worthwhile reviewing their methods and papers first before dismissing their conclusions. While some of the recent comments in this thread have made some incorrect statements (notably that no Starlinks would be visible above the horizon deep into the night), they seem to have generally come to an agreement that the lower orbital shell is preferable and that OneWeb is starting to become the major concern, in large part due to the lack of cooperation. My hope is that that changes now that the UK is involved. I'm sure they fund some amount of astronomical research, and it'd be counterproductive if their investment in OneWeb caused them to get less value from other investments they've made in research.

Here's the most recent posted webcast from the AAS on this topic which I'm pretty sure was posted upthread:
At a minimum I recommend reviewing Pat Seitzer's talk.

SpaceX has already *officially* pulled any satellites above 500km, in part because their discussions with the AAS helped make them conclude that higher altitudes make things worse (pretty sure that's said in a tweet somewhere or in one of recent AAS discussions on megaconstellations). I believe this is already reflected by their latest filings.

[thirtyone]

Great resource with exactly the same name as the thread (did the thread or post come first??? NSF member maybe?):

https://aas.org/posts/advocacy/2020/06/impacts-large-satellite-constellations-astronomy-live-updates

[ncb1397]

Below is a quick comparison between satellite charts for one web and spacex for two points in time from the previously mentioned ground station. Starlink is 72 orbital planes with 22 satellites each at 53 degree inclination and 550 km altitude. One Web is 18 orbital planes of 36 satellites each at 87.9 degree inclination at 1200 km. Note that the movement of satellites within orbital planes is much faster than the speed of the orbital planes through the sky. From my eye, they appear to interfere with a similar amount of the sky (in both cases, more starlinks are visible and are higher magnitude as well).

You are picking just a couple specific points in time, but this completely fails to illustrate the fact shown in multiple plots above that the higher altitude satellites are visible throughout the entire night (except maybe a small period for the smallest OneWeb shell in Jonathan Mcdowell's plot, hard to say due to the scale) While the Starlink illuminated satellites above low elevation (using an angle chosen by someone who is an astronomer) drops to zero for the majority of the night (defined by astronomical twilight.) This has been shown with more complete analysis than anything you have done, and from multiple sources.

Below is a time series for OneWeb in summer on January 19th again (which is somewhat of a worse or at least bad case scenario). Pick a constellation, say Orion, and you get interference in 1 out of 10 frames. Orion is about 500 square degrees in area and so the impact to something with Vera Rubin's massive 10 square degree field of view is probably very small(~50 times smaller than Orion). Anyways, there are about 42,000 stars in the night sky with 8.0 magnitude or brighter. Meaning in the time series, about every square degree on average would have such an object. Detectors are going to, by default, have to deal with that magnitude without effecting the electronics negatively (especially for the wide surveys everybody is worried about). At 5th magnitude, it is about 1600 (of which there are 500-600 starlinks at that magnitude currently in orbit with no apparent plans to de-orbit) and so treating them differently is completely valid. The combination of low total number of satellites, lower magnitude makes OneWeb's current efforts and deployment probably pretty small for even Vera Rubin(which everybody seems to agree is the hard test case). Arguably, OneWeb if they want browny points just needs to darken their satellites by a factor of 2.5 to magnitude ~9 (I'm still interested in more accurate magnitude measurements as a whole magnitude is a broad range). I'm also interested in anecdotes of effected observations or studies. We seem to have gotten that from the very first launch from Starlink with 3-4% deployment but I haven't seen anything for OneWeb with ~1% at operational altitude.

[ChrisWilson68]

I vote we split this thread into two.

Thread 1 will be for discussion based on the best evidence offered by detailed studies by professional astronomers.

Thread 2 will be for people who want to ignore the studies by professional astronomers and instead push their own pet theories based on their own original research.

[Dizzy_RHESSI]

Below is a quick comparison between satellite charts for one web and spacex for two points in time from the previously mentioned ground station. Starlink is 72 orbital planes with 22 satellites each at 53 degree inclination and 550 km altitude. One Web is 18 orbital planes of 36 satellites each at 87.9 degree inclination at 1200 km. Note that the movement of satellites within orbital planes is much faster than the speed of the orbital planes through the sky. From my eye, they appear to interfere with a similar amount of the sky (in both cases, more starlinks are visible and are higher magnitude as well).

You are picking just a couple specific points in time, but this completely fails to illustrate the fact shown in multiple plots above that the higher altitude satellites are visible throughout the entire night (except maybe a small period for the smallest OneWeb shell in Jonathan Mcdowell's plot, hard to say due to the scale) While the Starlink illuminated satellites above low elevation (using an angle chosen by someone who is an astronomer) drops to zero for the majority of the night (defined by astronomical twilight.) This has been shown with more complete analysis than anything you have done, and from multiple sources.

Below is a time series for OneWeb in summer on January 19th again (which is somewhat of a worse or at least bad case scenario). Pick a constellation, say Orion, and you get interference in 1 out of 10 frames. Orion is about 500 square degrees in area and so the impact to something with Vera Rubin's massive 10 square degree field of view is probably very small(~50 times smaller than Orion). Anyways, there are about 42,000 stars in the night sky with 8.0 magnitude or brighter. Meaning in the time series, about every square degree on average would have such an object. Detectors are going to, by default, have to deal with that magnitude without effecting the electronics negatively (especially for the wide surveys everybody is worried about). At 5th magnitude, it is about 1600 (of which there are 500-600 starlinks at that magnitude currently in orbit with no apparent plans to de-orbit) and so treating them differently is completely valid. The combination of low total number of satellites, lower magnitude makes OneWeb's current efforts and deployment probably pretty small for even Vera Rubin(which everybody seems to agree is the hard test case). Arguably, OneWeb if they want browny points just needs to darken their satellites by a factor of 2.5 to magnitude ~9 (I'm still interested in more accurate magnitude measurements as a whole magnitude is a broad range). I'm also interested in anecdotes of effected observations or studies. We seem to have gotten that from the very first launch from Starlink with 3-4% deployment but I haven't seen anything for OneWeb with ~1% at operational altitude.

The apparent magnitude that will cause detector issues for LSST is not the same at different orbital altitudes. The higher satellites take longer to move across the detector, meaning that the trail is brighter in the images. It's also been noted that the higher satellites are more focused for LSST, which further increases the surface brightness.

It's also not the case that astronomers don't care about fainter trails, it will still lead to lost data. To quote Tony Tyson's presentation at EAS "Even if [the darkening of starlink satellites] works, the satellite trails will remain at S/N~100 - complicating data analysis and limiting discoveries". Even if OneWeb doesn't reach into the regime of non-linear effects it will still lead to a lot of data being thrown away. The reason their scared of cross-talk is because they would really have to throw out significantly more data per trail. Having satellites which are illuminated for longer into the night will also result in more data being thrown out, as there will be more trails.

[ncb1397]

Below is a quick comparison between satellite charts for one web and spacex for two points in time from the previously mentioned ground station. Starlink is 72 orbital planes with 22 satellites each at 53 degree inclination and 550 km altitude. One Web is 18 orbital planes of 36 satellites each at 87.9 degree inclination at 1200 km. Note that the movement of satellites within orbital planes is much faster than the speed of the orbital planes through the sky. From my eye, they appear to interfere with a similar amount of the sky (in both cases, more starlinks are visible and are higher magnitude as well).

You are picking just a couple specific points in time, but this completely fails to illustrate the fact shown in multiple plots above that the higher altitude satellites are visible throughout the entire night (except maybe a small period for the smallest OneWeb shell in Jonathan Mcdowell's plot, hard to say due to the scale) While the Starlink illuminated satellites above low elevation (using an angle chosen by someone who is an astronomer) drops to zero for the majority of the night (defined by astronomical twilight.) This has been shown with more complete analysis than anything you have done, and from multiple sources.

Below is a time series for OneWeb in summer on January 19th again (which is somewhat of a worse or at least bad case scenario). Pick a constellation, say Orion, and you get interference in 1 out of 10 frames. Orion is about 500 square degrees in area and so the impact to something with Vera Rubin's massive 10 square degree field of view is probably very small(~50 times smaller than Orion). Anyways, there are about 42,000 stars in the night sky with 8.0 magnitude or brighter. Meaning in the time series, about every square degree on average would have such an object. Detectors are going to, by default, have to deal with that magnitude without effecting the electronics negatively (especially for the wide surveys everybody is worried about). At 5th magnitude, it is about 1600 (of which there are 500-600 starlinks at that magnitude currently in orbit with no apparent plans to de-orbit) and so treating them differently is completely valid. The combination of low total number of satellites, lower magnitude makes OneWeb's current efforts and deployment probably pretty small for even Vera Rubin(which everybody seems to agree is the hard test case). Arguably, OneWeb if they want browny points just needs to darken their satellites by a factor of 2.5 to magnitude ~9 (I'm still interested in more accurate magnitude measurements as a whole magnitude is a broad range). I'm also interested in anecdotes of effected observations or studies. We seem to have gotten that from the very first launch from Starlink with 3-4% deployment but I haven't seen anything for OneWeb with ~1% at operational altitude.

The apparent magnitude that will cause detector issues for LSST is not the same at different orbital altitudes. The higher satellites take longer to move across the detector, meaning that the trail is brighter in the images. It's also been noted that the higher satellites are more focused for LSST, which further increases the surface brightness.

Being out of focus is a double edged sword. It will inherently affect more pixels, but as you note, the brightness per pixel will be lower. As far as the angular velocity of the satellites, that also is a double edged sword. The faster they are, the longer the streaks meaning they are more likely to intersect a given exposure time.

As far as the effect of the change in angular velocity on the per pixel brightness of an object, Pat Sietzer indicated up thread that it reduces the effect of doubling altitude from a factor of 4 dimming (per pixel) to a factor of 2.8 (or from 25% to ~36%). As such, the brightening effect is ~44%. OneWeb is currently ~40% of the indicated threshold(8.0 magnitude compared to 7) for causing ghosting in the LSST detectors meaning you would need a 150% increase, not 44%.

Anyways, Pat Sietzer has indicated in the January press conference that the astonomical community thought they could live with 9th and 10th magnitude. OneWeb currently isn't far from that. What they really had a problem with was stuff much brighter than that.

[ChrisWilson68]

Anyways, Pat Sietzer has indicated in the January press conference that the astonomical community thought they could live with 9th and 10th magnitude. OneWeb currently isn't far from that. What they really had a problem with was stuff much brighter than that.

What was the context for Pat Seitzer's statement?  Was he talking about Starlink?  You haven't cited any source, so we can't tell what he was talking about.  You can't say that a magnitude that isn't a problem for Starlink isn't a problem for OneWeb.  It makes no sense.  There are lots of other factors besides magnitude.

You brought up Pat Seitzer.  So let's see what he actually had to say about OneWeb.  And I'll cite my source so everyone can check for themselves exactly what he said and what the context was:

Six OneWeb demonstration satellites are currently in orbit, at altitudes higher than SpaceX. Seitzer said the satellites, at about eighth magnitude, are too dim to be seen by the naked eye, but pose in some cases greater concerns to professional astronomers than Starlink satellites because, at their altitudes, they may be visible all night during the summer, rather than just around sunset and sunrise.

https://spacenews.com/spacex-astronomers-working-to-address-brightness-of-starlink-satellites/

This was in January.  Before SpaceX had done anything at all to mitigate Starlink brightness.  And yet the same person you're using to back up your claims actually explicitly says the opposite, and says what everyone else on this thread has been saying: the OneWeb altitudes are a problem.

[Dizzy_RHESSI]

Being out of focus is a double edged sword. It will inherently affect more pixels, but as you note, the brightness per pixel will be lower. As far as the angular velocity of the satellites, that also is a double edged sword. The faster they are, the longer the streaks meaning they are more likely to intersect a given exposure time.

The rate of incidence is a different question. If you start thinking about that then you cannot ignore the fact that the higher satellites are illuminated for much longer. This is why people are doing simulations.

OneWeb is currently ~40% of the indicated threshold(8.0 magnitude compared to 7) for causing ghosting in the LSST detectors meaning you would need a 150% increase, not 44%.

This is not in line with what was said at EAS by Tony Tyson. One question was raised about observations of the current OneWeb satellites and the answer was "Their trails have about the same surface brightness as a 7th mag satellite at 550km.   Unfortunately the big problem is they are visible all night long!"

Anyways, Pat Sietzer has indicated in the January press conference that the astonomical community thought they could live with 9th and 10th magnitude. OneWeb currently isn't far from that. What they really had a problem with was stuff much brighter than that.

Asking if people could live with some 9th magnitude satellites only half of the information. Would the answer be the same if you said there was going to be 48,000 of them? No. Tyson also said at EAS that "any constellation at 1200 km would be particularly destructive".

[ncb1397]

Anyways, Pat Sietzer has indicated in the January press conference that the astonomical community thought they could live with 9th and 10th magnitude. OneWeb currently isn't far from that. What they really had a problem with was stuff much brighter than that.

What was the context for Pat Seitzer's statement?  Was he talking about Starlink?  You haven't cited any source, so we can't tell what he was talking about.  You can't say that a magnitude that isn't a problem for Starlink isn't a problem for OneWeb.  It makes no sense.  There are lots of other factors besides magnitude.

You brought up Pat Seitzer.  So let's see what he actually had to say about OneWeb.  And I'll cite my source so everyone can check for themselves exactly what he said and what the context was:

Six OneWeb demonstration satellites are currently in orbit, at altitudes higher than SpaceX. Seitzer said the satellites, at about eighth magnitude, are too dim to be seen by the naked eye, but pose in some cases greater concerns to professional astronomers than Starlink satellites because, at their altitudes, they may be visible all night during the summer, rather than just around sunset and sunrise.

1.)Your quote that you characterize as "exactly" what he said isn't a direct quote
2.)The source has already been linked to in this thread, but here goes.

What was totally surprising was how bright the starlinks were. You know, we thought if they were 9th or 10th....
hey, we could live with that. But third magnitude? 5th mangitude? That is far brighter than we had any reason to expect and it turned out SpaceX hadn't expected them to be that bright. So, yes, we should have been aware of that, but there are many many objects in earth orbit that are similar sizes (rocket bodies, defunct satellites) at anywhere from 400 to 1200 km that are much fainter. And what is really surprising about the SpaceX satellites is how bright they are.

You can consider the OneWeb satellite altitudes as a problem, but on the other hand, there are many attributes other than altitude that mitigate this (satellite number, satellite brightness, high inclination, single inclination, less orbital planes,etc.). So, in terms of which constellation will have a greater impact on astronomy, it is probably going to be the 500+ mag 5 starlinks, not the 600+ mag 8 (or possibly dimmer if they do mitigation) OneWebs. And that is born out by reported impacts that are public so far of 60 non-mitigated starlinks almost immediately after launch compared to the complete lack of reported impacts from 10% as many operational altitude OneWebs that have been in orbit for ~17 months. If that is a false impression that astronomers are portraying by only talking about starlink impacts, then that is something that needs to be corrected (ASAP).

[ChrisWilson68]

What was totally surprising was how bright the starlinks were. You know, we thought if they were 9th or 10th....
hey, we could live with that. But third magnitude? 5th mangitude? That is far brighter than we had any reason to expect and it turned out SpaceX hadn't expected them to be that bright. So, yes, we should have been aware of that, but there are many many objects in earth orbit that are similar sizes (rocket bodies, defunct satellites) at anywhere from 400 to 1200 km that are much fainter. And what is really surprising about the SpaceX satellites is how bright they are.

Thank you for proving my point.  The quote you cited was explicitly talking about Starlink, then you applied it to OneWeb.  They aren't the same.

You can consider the OneWeb satellite altitudes as a problem, but on the other hand, there are many attributes other than altitude that mitigate this (satellite number, satellite brightness, high inclination, single inclination, less orbital planes,etc.).

Which is why everyone else on this thread is paying attention to what professional astronomers who have studied all the factors together are saying.  They are saying OneWeb is more of a concern.

For some reason you are ignoring them and ignoring many of the relevant factors.  You're picking just certain factors and doing your own analysis, which conflicts with the analysis of the professional astronomers.

So, in terms of which constellation will have a greater impact on astronomy, it is probably going to be the 500+ mag 5 starlinks, not the 600+ mag 8 (or possibly dimmer if they do mitigation) OneWebs.

It's probably going to be?  So you want other people to believe your wild guess that the other factors don't matter, rather than what the studies of professional astronomers say?

Sorry, but that's not convincing.

And that is born out by reported impacts that are public so far of 60 non-mitigated starlinks almost immediately after launch compared to the complete lack of reported impacts from 10% as many operational altitude OneWebs that have been in orbit for ~17 months.

So now instead of careful studies by professional astronomers you want to base conclusions on popular media reports?

We know why there has been more reported in the popular press about the Starlinks -- because they form a highly-visible "string of pearls" that non-specialists can see with no equipment.  That attracts attention.  OneWeb doesn't have that visibility.  So it's not in the media as much.  That doesn't mean it isn't a problem.

Again and again and again you are appealing to bad sources while ignoring good sources.

If that is a false impression that astronomers are portraying by only talking about starlink impacts, then that is something that needs to be corrected (ASAP).

It's not a false impression from astronomers.  It's a false impression from the popular media.  And a false impression from people like you who ignore the actual detailed studies by astronomers.  And I agree that it needs to be corrected.  That's what all the people you are arguing against are trying to do.