Albuquerque, NM.Both n2yo and SatFlare forecast a good viewing opportunity with nearest approach to zenith about 9:41 p.m. at about 86 degrees.I went to my roof with a pair of 10x42 image-stabilized binoculars of excellent optical quality and was very glad I had them.I'm about ten miles from the city center, and the satellites rose just about over the city, so in a bright part of the light pollution. I scanned the SW horizon back and forth with the binoculars, and first saw three dots travelling fast in perfect train. For a surprising number of seconds I could only see those three through the binoculars, and nothing with naked eye. As the train approached zenith I saw many more--eventually about thirty, with my "bright three" mixed in with many other dimmer ones.The time of nearest approach to zenith was quite close to the n2yo and SatFlare forecast, within a minute or two. The "bright three" were moderately dimmer than the stars of Ursa Major (the Big Dipper) and the others were much dimmer. Even near zenith not many were naked eye visible here beyond the bright three.Today was windy, so seeing was probably a bit dust impaired. Also the city is close enough to impose appreciable light pollution. For reference, while I could easily locate all of the primary stars of the Big Dipper, I could only confidently locate Polaris in the Little Dipper. The two dominant features were fast movement relative to the stellar background (or even airplanes), and movement in near-perfect train.
Quote from: archae86 on 05/27/2019 04:02 amAlbuquerque, NM.Both n2yo and SatFlare forecast a good viewing opportunity with nearest approach to zenith about 9:41 p.m. at about 86 degrees.I went to my roof with a pair of 10x42 image-stabilized binoculars of excellent optical quality and was very glad I had them.I'm about ten miles from the city center, and the satellites rose just about over the city, so in a bright part of the light pollution. I scanned the SW horizon back and forth with the binoculars, and first saw three dots travelling fast in perfect train. For a surprising number of seconds I could only see those three through the binoculars, and nothing with naked eye. As the train approached zenith I saw many more--eventually about thirty, with my "bright three" mixed in with many other dimmer ones.The time of nearest approach to zenith was quite close to the n2yo and SatFlare forecast, within a minute or two. The "bright three" were moderately dimmer than the stars of Ursa Major (the Big Dipper) and the others were much dimmer. Even near zenith not many were naked eye visible here beyond the bright three.Today was windy, so seeing was probably a bit dust impaired. Also the city is close enough to impose appreciable light pollution. For reference, while I could easily locate all of the primary stars of the Big Dipper, I could only confidently locate Polaris in the Little Dipper. The two dominant features were fast movement relative to the stellar background (or even airplanes), and movement in near-perfect train.I just watched the train pass overhead, and contrary to the delight I expected to feel, I was horrified. My friend had been tracking them, and I've been running outside periodically to look up.I realized tonight that I prize the stillness of the night sky. I don't want to look up at the stars and see constant motion. I hope there's something they can do to make the satellites non-reflective. I've rooted for everything SpaceX has ever done until tonight, but to quote my friend, given the choice between Starship hitting all of its aspirational targets and opening up the solar system, and looking up to see thousands of Starlinks, I'd rather have SpaceX go away tomorrow. Same goes for Amazon's constellation and all the others. No thanks.
Besides, enough with the hyperbole already. There won't be "thousands of satellites in the sky"... They are in LEO. There will be maybe a dozen within line of sight from any given point on Earth, and they will only be visible during windows around dusk/dawn
Quote from: meekGee on 05/27/2019 08:50 amBesides, enough with the hyperbole already. There won't be "thousands of satellites in the sky"... They are in LEO. There will be maybe a dozen within line of sight from any given point on Earth, and they will only be visible during windows around dusk/dawnWhen the constellation is finished, about 500 will be overhead any particular person at any given time. Last night one of the space photographers I follow saw the third pass over Chicago, which was after midnight, I think. That's 4 hours after local sunset, and local sunrise there is at 5:20, you you'd expect passes 4 hours before sunrise then as well. That leaves an hour of night (assuming no visible pass is possible in the intervening hour). Of the 64 tracked objects, last night 3 were at least magnitude 2 (at least as bright as the brighter stars in Ursa Major), and they were bright for the whole pass (SW-->NE). Others flickered in and out of naked eye visibility (in a small city, would have been more someplace dark). Let's assume 5% are visible. That means when all 12000 are up, 25-50 will be as bright as the stars commonly visible in a small city for every observer all the time (counting on the same number popping in and out of visibility). That's actually not as bad as I had thought, but in the back country that likely becomes over 100 visible for at least 8 hours of each night given reports of visible passes well after midnight.Astronomers can deal with this, and Elon has tweeted they can put space telescopes up. I'm not concerned with the astronomy at the moment, I'm concerned with quality of life for all of us here on Earth. It seems like mitigating this would simply be good planetary citizenship. Anti-reflective coatings on the Earth-facing plane of the spacecraft, for example. The goal should be to try and get each sat below mag 6.5 (naked eye limit). If this can be achieved with coatings, why would anyone be against this? Pretending it's not an issue at all doesn't provide any incentive to bother fixing the problem. The engineering balance is thermal management and weight vs creating an eyesore. It's not like a quarter wave coating is going to add much weight.I should add that random sat passes are different than a visible pattern. Humans notice patterns, and that nature of these constellations (there will be more) will make them even more obvious. What happens some other nation does the same, but the sats are bigger, or more reflective? Seems like the standard should be set now to intentionally minimize visual impact.
500 at any given time - doesn't that mean they have too many satellites?Concern - for sure, evaluate it first, and then if it bothers people, do the best you can to improve...
My issue is with lack of proportion in the responses, and the failure to understand just how fundamentally important this is.
It seems like mitigating this would simply be good planetary citizenship. Anti-reflective coatings on the Earth-facing plane of the spacecraft, for example. The goal should be to try and get each sat below mag 6.5 (naked eye limit). If this can be achieved with coatings, why would anyone be against this?
Chicago at midnight - can you explain how that happens? I'm really curious.
The horizon for a 500 km tower is 10000 km away.
Quote from: meekGee on 05/27/2019 04:28 pmThe horizon for a 500 km tower is 10000 km away.Uh, no. Opinions about a dark sky are one thing. Opinions about basic geometry are something else entirely.
Quote from: meekGee on 05/27/2019 05:52 pmThe horizon for a 500 km tower is 10000 km away.Check your math. 10000 km is the distance from the pole to the equator. 500 km is just 1/12 the Earth's radius. Intuition should tell you that a object less than (say) a half inch above the top of a basketball is not going to be visible at the "equator".I get arccos(r/(r+h))*r = 2400 km for r=6371km and h=500km. But that's all the way down to the horizon. Obviously it will be less if want the satellite visible higher in the sky.
