Re: Is Gauss Method really so inputs sensitive? (Orbit Determination with Starlink observations from GoPro)

From: Andreas Hornig via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 2 Aug 2020 00:28:47 +0200
Hi Marco and the others,

On Sat, Aug 1, 2020 at 10:42 PM Marco Langbroek <marco_at_langbroek.org> wrote:

>
> It is important to note that getting 'good' elements from a single pass is
> impossible. You will need multiple passes to constrain elements like Mean
> Motion.
>

I know. There will always be a difference between numerical result and
reality.
But what I do not know yet and try to understand is what is considered
"good" for amateur observations or for professional measurements like what
NORAD is doing for decades and what LeoLabs and others are now also trying
to do.
I am asking because I would like to know to what residual level I should
keep my optimizer running. It is quickly converging but then it is
searching quite longly for better solutions. I do not want it to run for
hours when I can also stop it earlier.

So with the result I sent before, I am just a few kilometers short of the
apogee and perigee of the TLEs that I compare them with. For me, that was
better than expected. But it is still a few kilometers.
So what is a measure for "good" here? Is it kilometers, meters?


And because I received a few direct emails (btw I prefer public
conversations ;)), that was my location of the measurements

8888 AH   50.9157   11.7199    406    Andreas Hornig

and the IOD data, that is also in the initial google drive spreadsheet, is this:

Starl nk 123A   8888 F 20200420193016000 17 25 0642970+000773 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193026000 17 25 0651246+020261 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193028000 17 25 0653903+022786 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193038000 17 25 0703790+043819 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193042000 17 25 0707972+052686 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193052000 17 25 0719837+075880 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193054000 17 25 0724855+085640 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193104000 17 25 0739710+115653 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193108000 17 25 0745820+130380 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193118000 17 25 0805747+164463 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193122000 17 25 0813454+180355 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193132000 17 25 0839976+222241 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193134000 17 25 0850166+235012 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193144000 17 25 0924940+282582 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193148000 17 25 0937780+294893 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193158000 17 25 1021916+335728 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193200000 17 25 1037313+350290 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193210000 17 25 1127895+374378 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193214000 17 25 1144044+381282 56 S-015 10 010000
Starl nk 123A   8888 F 20200420193224000 17 25 1233781+385452 56 S-115 10 010000
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Received on Sat Aug 01 2020 - 17:30:01 UTC

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