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ANOTHER source of "astronomical" pollution.



 
 
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  #11  
Old February 1st 18, 12:51 AM posted to sci.astro.amateur
Chris L Peterson
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Posts: 10,007
Default 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  
Old February 1st 18, 07:39 AM posted to sci.astro.amateur
Paul Schlyter[_3_]
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Posts: 1,344
Default 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  
Old February 1st 18, 03:34 PM posted to sci.astro.amateur
Chris L Peterson
external usenet poster
 
Posts: 10,007
Default 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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