I am trying to verify a three body simulation and for that need actual planetary position data from out solar system, but I cannot find any. I need it in barycentric coordinates, does anyone know where to find such? It would also be ok if they were from another simulation, if this is verified. Thank you in advance!
Hello,
At http://ssd.jpl.nasa.gov/ there are, among other information, tools to generate ephemerides of planets and minor bodies of the Solar System.
Funny, I was looking for this and could not find it. Only the small body database. Thank you a lot! Very helpful!!! and also good to know I did not imagine a database like that. ;)
You can also directly access (via FORTRAN, C, IDL, MATLAB, or Java) the planetary and spacecraft ephemeris kernels provided by JPL at the Navigation and Ancillary Information Facility (NAIF) site. The SPICE library provides hundreds of functions that will return position data in a number of reference frames, and also perform computations regarding spacecraft and instrument pointing.
They also provide an excellent online tutorial for using every aspect of the SPICE Toolkit.
http://naif.jpl.nasa.gov/naif/
JPL Horizons - Gennaro D'Angelo has already given the link - http://ssd.jpl.nasa.gov/ . It has a really good interface, and is quite complete. If you really worry about errors or incompleteness in the JPL model, you probably need to start doing your own integrations.
Horizons has its uses, but if you want your own program to be able to do a time-based lookup of a the ephemeris of a body then you want to use SPICE, as recommended by Paul Wren above. SPICE is a comprehensive geometry toolkit with an interface for describing positional and attitudinal ephemerides. The learning curve is steep, but the effort is well worth it and you will never look back.
Once you have the kernels set up and loaded into your program, your problem will be reduced to a call like this:
spkezr("JUPITER", EphTime, "J2000", "LT+S", "My Comet", state, lighttime);
C shown here; other languages are similar; as Paul Wren says there are many other languages. including a developing but functional Python interface.
I am a bit of an evangelist for SPICE and would be glad to help you get started.
As most already mentioned, you can easily find that information at http://ssd.jpl.nasa.gov/. Hope this helps!
Here are nice lecture notes on writting your own planetary simulator using Runge-Kutta method: http://www.physics.buffalo.edu/phy410-505/2011/topic2/app1/index.html , initial positions of planets can be taken from PyEphem: http://rhodesmill.org/pyephem/ or jplephem https://pypi.python.org/pypi/jplephem
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