TLE Propagator Parameters

[bcazabonne]

Hi @astroboy

Welcome to the Orekit forum!

Your code is good.

As explained in the topic below, TLE parameters are significant only with respect to the TLE propagation model (i.e., SGP4 model represented by the TLEPropagator class of Orekit)

DSST Propagation results seems odd

Hi @JulienL for i in range(len(TLEs)): tle_i.append(TLEs[i].getI()) tle_omega.append(TLEs[i].getRaan()) tle_e.append(TLEs[i].getE()) tle_arg.append(TLEs[i].getPerigeeArgument()) tle_M.append(TLEs[i].getMeanAnomaly()) tle_date.append(TLEs[i].getDate()) tle_meanMotion.append(TLEs[i].getMeanMotion()) You can’t use directly the orbital parameters contained in the TLE. These parameters are only significant with respect to the propagation model (e.g. SGP4). Therefore, yo…

We can’t directly use the keplerian elements contained in the TLE. In other words, the keplerian elements printed by

print(tle_line_1)
print(tle_line_2)

are not the good ones. The correct ones are those calculated by

tle_propagator = TLEPropagator.selectExtrapolator(tle_object)
tle_orbit_cart = tle_propagator.getInitialState().getOrbit()
tle_orbit_kep = OrbitType.KEPLERIAN.convertType(tle_orbit_cart)

The JavaDoc of the TLE class explains this particularity.

Best regards,
Bryan