Data on Planetary Orbits

[Philosophaie]

I have developed a program calculating the orbits of the planets from Jet Propulsion Lab (JPL) data.

I am in need of the actual data of the planet's orbits for specific dates:

Argument of the Perihelion
True Anomaly
Mean Anomaly
Semi-Major Axis
Eccentricity
Longitude of the Ascending Node
etc

If someone could give me the name of some sort of book or almanac it would be much appreciated.

[Chris Peterson]

I have developed a program calculating the orbits of the planets from Jet Propulsion Lab (JPL) data.

I am in need of the actual data of the planet's orbits for specific dates:

Argument of the Perihelion
True Anomaly
Mean Anomaly
Semi-Major Axis
Eccentricity
Longitude of the Ascending Node
etc

If someone could give me the name of some sort of book or almanac it would be much appreciated.

I'm not sure what you're asking for. Orbital elements are not a function of time, although unstable elements are periodically updated. Planetary elements are very stable, however. Are you simply looking for the values of the six classical Keplerian elements (which would not be strictly associated with any particular time), or are you looking for actual state vectors for the planets at specific times so you can test your propagator?

The classical elements for the planets are available here, valid with a small error for 3000 BCE to 3000 CE. If you need more accuracy in your calculations, you should not be using Keplerian elements at all, but a more complex system, using either series with many terms or dynamic integration.

If you're looking for orbital state data, I'd suggest the JPL Horizons propagator, which will provide much more accurate output than any Keplerian approach can.

[Philosophaie]

For now I will stick with Keplerian Classical Elements. I knew about both sites previously mentioned. They do give equations and the final results of RA,DEC,eclLong, etc. They both do not give the correct Keplerian data (listed above) for a specific times.

[Chris Peterson]

For now I will stick with Keplerian Classical Elements. I knew about both sites previously mentioned. They do give equations and the final results of RA,DEC,eclLong, etc. They both do not give the correct Keplerian data (listed above) for a specific times.

There normally is no Keplerian data for specific times. Keplerian element sets are independent of time (although mean anomaly defines the body's position in the orbit at a specific time). Except for highly perturbed bodies, element sets are not generated for specific times.

I doubt you'll find Keplerian elements for planets generated at arbitrary times. Most applications simply use the set I linked. You could use Horizons to get accurate positions for specific times, and then generate the elements yourself, but I don't think you will improve significantly on accuracy over simply using the standard published elements.

[Philosophaie]

"Chris Peterson Wrote:
If you need more accuracy in your calculations, you should not be using Keplerian elements at all, but a more complex system, using either series with many terms or dynamic integration.

Could you please elaborate on the above methods. I am college educated ie Calculus and Physics. Any sites or book titles would be much appreciated.

[Chris Peterson]

Could you please elaborate on the above methods. I am college educated ie Calculus and Physics. Any sites or book titles would be much appreciated.

The standard method for solving for the positions of planetary bodies in the Solar System involves using a model called VSOP87 (which is publicly available). It is a set of coefficient tables used to calculate perturbed positions for these bodies. Depending on the desired accuracy, you can use some or all of the coefficients. Smaller bodies are calculated by using their Keplerian elements calculated for a known time, and then numerically integrating their position forward or backward in time, applying Newtonian equations of motion at each step (using the positions of the major planets).