Re: Modeling Starlink magnitudes in a simulation

From: Richard Cole via Seesat-l <>
Date: Tue, 2 Jun 2020 18:39:48 +0000

1. I did this simulation of a completed 1440 satellite first shell 
constellation some months ago. I tried to make the final sky simulation 
segment representative of standard (non-Darksat) Starlinks, that is just 
visible to the naked eye. They are quite hard to see in the video (which 
was the idea) (done with Heavensat).

2. Trying to simulate the brightness of spacecraft on the way up (the 
Trains in SpaceX's termed 'open-book mode') will need a lot of work to 
understand how the spacecraft are flown and hence how they appear to an 
observer. In any case SpaceX are now using Knife-edge mode which means 
the Trains are now much fainter and not spectacular. SpaceX has stated 
that the first few days of each mission will be bright, but then the 
spacecraft will be put into the darker knife-edge mode. My suggestion 
would be to stick to simulation of the deployed Starlinks.

3. The Starlink constellation design is changing all the time. A new 
application for a 30000 spacecraft Gen2 constellation was made a couple 
of weeks ago. How that matches to the current constellation now in 
build, or the one originally proposed, or the modification to that 
proposed a while ago, is anyone's guess. Or whether all the current 
plans will be replaced with new ones before they are implemented.

Gen 2 application

and a simulation

Good luck with the project. I will be interested in the result.


Richard Cole

On 02/06/2020 14:42, Max Hartshorn via Seesat-l wrote:
> Hi All,
> I'm new to this list and new to satellite observation. My name is Max
> Hartshorn and I'm a computer programmer and data journalist based in
> Toronto, Canada. I became interested in Starlink after I inadvertently
> witnessed the initial load shortly after the launch last May. They were by
> far the brightest objects in the sky...though I understand their apparent
> magnitudes will have decreased considerably once they reached their final
> orbit.
> What I'd like to do is create a *responsible* and *non alarmist*
> visualization of what the night sky *could* look like when 12,000 Starlink
> satellites are up and running. As far as I know such a simulation does not
> exist.
> I've been playing around with Stellarium and TLEs and I can see that it's
> possible to generate a TLE file for 12,000 satellites at roughly the
> configuration proposed by Starlink, and model those orbits in Stellarium.
> But the big open question is around magnitudes.
> I've been looking through the archives here and I've seen a range of
> apparent magnitude observations, anywhere from 2 to 9. Additionally
> Starlink is iterating the design of their satellites to minimize
> reflectivity.
> The threshold that's most interesting to me is the 6.5 threshold for naked
> eye observation. If the satellites (particularly those in the lower orbital
> shells) are below that threshold, they could potentially impact how the
> general public views the night sky.
> Is there any agreed upon estimate for the apparent magnitude of the
> Starlink satellites currently in orbit? Do we just not know yet? Are there
> any responsible methods for modeling / estimating the magnitude of the
> remaining satellites?
> Sorry for the long email. I figure if anybody would know the answers to
> these questions it would be you folks :)
> Thanks,
> Max
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Received on Tue Jun 02 2020 - 13:40:45 UTC

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