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#11
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ANOTHER source of "astronomical" pollution.
On Wed, 31 Jan 2018 22:47:04 +0100, Paul Schlyter
wrote: On Mon, 29 Jan 2018 16:34:50 -0700, Chris L Peterson wrote: On Mon, 29 Jan 2018 21:16:07 +0100, Paul Schlyter wrote: On Sun, 28 Jan 2018 09:03:13 -0700, Chris L Peterson wrote: It is likely to be worse than either, because it is so bright, and because it is bright across its entire path, not just in a flare zone. No, it's not bright across its entire path. It has 72 reflective triangular surfaces. Only half of then can be effective of course since the other half will be in shadow. And less than half of those will shine towards the Earth, the others will shine into space. So it will generate some 15 flare zones, each giving flares considerably fainter than Iridium. That assumes the satellite is not changing orientation. The description I've read says it is deliberately placed in a tumbling orbit so everyone sees a sparkling path. No it doesn't assume that. Flare zones can have irregular shapes, and they will as the ball tumbles. Sure. But the whole point is that glints will be widely seen. Just like you get with a disco ball. Not just a single flare from a small area as with Iridiums. |
#12
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ANOTHER source of "astronomical" pollution.
On Wed, 31 Jan 2018 16:51:57 -0700, Chris L Peterson
wrote: On Wed, 31 Jan 2018 22:47:04 +0100, Paul Schlyter wrote: On Mon, 29 Jan 2018 16:34:50 -0700, Chris L Peterson wrote: On Mon, 29 Jan 2018 21:16:07 +0100, Paul Schlyter wrote: On Sun, 28 Jan 2018 09:03:13 -0700, Chris L Peterson wrote: It is likely to be worse than either, because it is so bright, and because it is bright across its entire path, not just in a flare zone. No, it's not bright across its entire path. It has 72 reflective triangular surfaces. Only half of then can be effective of course since the other half will be in shadow. And less than half of those will shine towards the Earth, the others will shine into space. So it will generate some 15 flare zones, each giving flares considerably fainter than Iridium. That assumes the satellite is not changing orientation. The description I've read says it is deliberately placed in a tumbling orbit so everyone sees a sparkling path. No it doesn't assume that. Flare zones can have irregular shapes, and they will as the ball tumbles. Sure. But the whole point is that glints will be widely seen. Just like you get with a disco ball. Not just a single flare from a small area as with Iridiums. Glints are preferable to continuous light, and this satellite will be less disturbing than Echo II was. And are there any observers of faint DSO's or some other objects so they want the darkest possible skies who check for Iridium flares during their observing session and move elsewhere if they would be unfortunate to encounter one? |
#13
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ANOTHER source of "astronomical" pollution.
On Thu, 01 Feb 2018 07:39:48 +0100, Paul Schlyter
wrote: Sure. But the whole point is that glints will be widely seen. Just like you get with a disco ball. Not just a single flare from a small area as with Iridiums. Glints are preferable to continuous light, and this satellite will be less disturbing than Echo II was. And are there any observers of faint DSO's or some other objects so they want the darkest possible skies who check for Iridium flares during their observing session and move elsewhere if they would be unfortunate to encounter one? I don't personally consider this thing to be "disturbing" at all. It's a stunt. Whether such things become a problem in the future remains to be seen. I think it is reasonable to consider an international treaty that places constraints on what can be sent to orbit based on utility. Professional observing sessions (and possibly some amateur sessions) do sometimes involve checking for satellite interference. |
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