Re: planscan: Computing optimal directions for performing a plane scan

From: C. Bassa via Seesat-l <seesat-l_at_satobs.org>
Date: Mon, 15 Feb 2016 23:39:56 +0100
Hi Greg,

On Mon, Feb 15, 2016 at 7:42 AM, Greg Roberts via Seesat-l
<seesat-l_at_satobs.org> wrote:
> I am still a little puzzled why you need to specify the altitude of the
> satellite. You are using TLE's and either computing shadow entry or
> exit points or maximum brightness so you must be using the altititude
> given by the elements so why is there a need to specify the altitude?
> (to be honest I am being a little lazy here as I am trying to avoid
> having to use a prediction to get an idea of the altitude to enter in
> the command line.

The reason I ask the user to specify it is to force them to think
about what they are doing. For most objects in circular orbits the
mean altitude should be used, but for objects in eccentric LEO orbits
they will have to make a conscious choice. Consider trying to recover
the KH USA 224 in the coming spring after it has not been seen for at
least 7 months. We can expect it is still in its 270x1010 km orbit,
but we don't know if the argument of perigee is still correct. Most
likely it will have maneuvered and changed this. For this object it
wouldn't make much sense to search at the 640 km mean altitude.
Instead, the best strategy is to first perform plane searches on the
higher orbital altitudes where the object first becomes sunlit, and as
the season continues continue scanning lower and lower altitudes until
it is recovered.

However, I agree that for most cases the mean altitude will suffice.
I'll implement this in the next version.

Regards,
    Cees
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Received on Mon Feb 15 2016 - 16:40:39 UTC

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