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RE: [Orekit Users] computation of secular derivatives



Thank you Paul and Luc,

I am going to try this method soon.

Quentin


-----Original Message-----
From: orekit-users-request@orekit.org [mailto:orekit-users-request@orekit.org] On Behalf Of MAISONOBE Luc
Sent: Friday, January 26, 2018 5:04 PM
To: orekit-users@orekit.org
Subject: Re: [Orekit Users] computation of secular derivatives


paulcefo <paulcefo@buffalo.edu> a écrit :

> Quentin,
>
> The partial derivatives of the averaged potential (due to the  
> conservative perturbations) are required to construct the RHS of the  
> mean element equations of motion in the DSST. So the information  
> should be available interior to the DSST software.

Yes, they are available.

The state contains an orbit (equinoctial orbit for DSST) and since version
9.0 the orbit provides methods like getAdot() and similar. If you have
set up your DSST propagator to compute mean elements only, you will
get the secular derivatives. Beware that for the mean longitude argument
it also includes the Keplerian motiion so if you want the non-Keplerian
part only you will beed to subtract orbit.getKeplerianMeanMotion (or
something similar if you need true or eccentric angles).

best regards,
Luc

>
> Paul
>
> -- 
> Dr. Paul J. Cefola
> Consultant in Aerospace Systems, Spaceflight Mechanics, & Astrodynamics
> Adjunct Faculty, Dept. of Mechanical and Aerospace Engineering,  
> University at Buffalo (SUNY)
>
> 4 Moonstone Way
> Vineyard Haven, MA 02568
> USA
>
> 508-696-1884 (phone on Martha's Vineyard)
> 978-201-1393 (cell)
>
> paulcefo@buffalo.edu
> paul.cefola@gmail.com
>
> On 01/26/2018 4:17 am, RHONE, Quentin [FR] wrote:
>> Hi all,
>> I am trying to compute secular derivative of orbital elements with
>> high potential degree so that I cannot use an analytic formula.
>> Is there a way to do it with Orekit ?
>> I have tried do get mean elements derivatives from DSST
>> computeMeanState method but the return state doesn't contain
>> derivatives.
>> Any suggestion will be welcome !
>> Thank you in advance,
>>
>> Quentin
>>
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