Position, velocity and acceleration of a body using JPL's DExxx ephemerides
[pos, vel, acc] = CL_ephDE_getPVA(body, cjd [[, orig, ephem, tt_tref, opts]])
Computes the position, velocity and acceleration of a body using JPL's DExxx ephemerides.
The results are given in the ICRF frame.
Available bodies are: "Mercury", "Venus", "Earth-Moon-bary" (or "EMB"), "Mars", "Jupiter", "Saturn", "Uranus", "Neptune", "Pluto", "Moon", "Sun", "Earth", "solar-sys-bary" (or "SSB")
The computed data are:
pos: vector from orig to body
vel: first time derivative of pos
acc: second time derivative of pos
By default, the function looks for the appropriate JPL's DE405 ephemeris files located in CL_home()/data/ephem/de405.
One can also specify the ephemerides to be used with the optional argument ephem. See CL_ephDE_load, CL_ephDE_loadT, or CL_ephDE_setPath.
The optional structure opts contains the optional fields:
- conv_to_tdb (boolean): if %f, the time scale used internally to retrieve the data is TT. Otherwise, TDB is used, which is more precise. By default: %t.
Notes:
- For dates that are not covered by the ephemeris file(s), %nan values are returned.
- The default value for the origin is the solar system barycenter (even for the Moon!)
- The results returned for all planets except Earth actually are the position velocity and acceleration of the barycenter of the planet system (i.e barycenter of planet + satellites).
- Body names are case sensitive.
- (advanced) Setting opts.conv_to_tdb to %f and tt_tref to 0 comes down to considering that cjd is actually given in the TDB time scale.
See Reference frames for more details on the ICRF frame, and Ephemerides for more details on ephemerides of celestial bodies.
(string) Name of the body. (1x1)
Modified (1950.0) julian day (Time scale: TREF) (1xN)
(optional, string) Name of the origin. Default is "solar-sys-bary" (1x1)
Scilab structure describing the ephemerides (see "See Also").
(optional) TT-TREF [s]. Default is %CL_TT_TREF. (1xN or 1x1)
(structure, optional). Additional options. See above for details.
Position of body, relative to orig, in ICRF frame [m] (3xN)
Velocity of body, relative to orig, in ICRF frame [m/s] (3xN)
Acceleration of body, relative to orig, in ICRF frame [m/s^2] (3xN)
CNES - DCT/SB