I am writing a Python code using your dedicated wrapper. I have created a KeplerianOrbit object in a standard way as
orbit = KeplerianOrbit(pvCoordinates, inertialFrame, initialDate, Constants.WGS84_EARTH_MU).
The aim of my work is to compute a range (in particular a one-way distance) measure between my satellite and a reference point, which is assumed to be fixed in time. This task is very easy and I already get my range measurements by simply considering the norm of r = r_sat - r_p, where r_sat is the 3D vector representing the satellite position in the inertialFrame and r_p is that of the reference point. So the code is able to collect a set of ranges r_1, r_2, … r_n, where a single range is computed every s seconds, while the satellite orbit is propagated through the propagator defined as
propagator = KeplerianPropagator(orbit).
Now, I would like to estimate the derivatives of my measurements r_1, r_2, … r_n with respect to the initial pvCoordinates I have chosen for the orbit. My problem here is that I don’t
know how to compute the derivatives of the satellite positions at the time instants t_1, t_2,… t_n in which the original range measurements were calculated.
Can you please tell me which is the most convenient way to carry out this step? I must admit I am new to Orekit and I don’t know if there is already a method allowing it. This code is related to a Batch estimator and the partial derivatives of the ranges have to be taken with respect to an integration function G, which depends on the initial pvCoordinates…