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Getting ephemeris data in heliocentric coordinates

George Hazelrigg, Retired
Posted 4 months ago

I am trying to use the JPL Horizons Ephemeris database to determine planetary positions and velocities in heliocentric coordinates. My code is:

ResourceFunction[
  "HorizonsEphemerisData"]["State", {Entity["Planet", "Earth"], <|
   "Dates" -> {DateObject[{2024, 4, 19}],
     DateObject[{2024, 7, 19 + 20}],
     Quantity[10, "Days"]}|>}, All, "Dataset", {"Position",
  "Velocity"}]

But this does not return data in heliocentric coordinates. Can anyone please suggest how I can get the position and velocity in heliocentric coordinates?
POSTED BY: George Hazelrigg
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Problem solved.

ResourceFunction["HorizonsEphemerisData"]["State", <|
  "Target" -> Entity["Planet", "Earth"], "Center" -> "@0",
  "Dates" -> {DateObject[{2024, 7, 19}],
    DateObject[{2024, 7, 19}] + Quantity[12, "Days"],
    Quantity[1, "Days"]}|>, {"Position", "Velocity"}, "Dataset"]

Must specify the "Center" as "@0". Had to look this up in the NASA documents on the Horizons database. I could not find any documentation on this by Mathematica.
POSTED BY: George Hazelrigg
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